Release v0.1.2 2026-07-11

package.json

@@ -1,7 +1,7 @@
 {
   "name": "i-want-to-heal",
   "private": true,
-  "version": "0.1.1",
+  "version": "0.1.2",
   "type": "module",
   "scripts": {
     "dev": "vite --host 0.0.0.0",

scripts/blender/build_ember_mantis_duelist.py

@@ -790,6 +790,7 @@ def write_metadata(body: bpy.types.Object, clips: dict[str, dict]) -> None:
 def main() -> None:
     OUT_DIR.mkdir(parents=True, exist_ok=True)
     PREVIEW_DIR.mkdir(parents=True, exist_ok=True)
+    bpy.context.preferences.filepaths.save_version = 0
     reset_scene()
     mats = {
         "chitin": make_material("M_Chitin", (0.025, 0.022, 0.026, 1), metallic=0.18, roughness=0.42),

src/components/GameScene.tsx

@@ -17,6 +17,7 @@ const SPIDER_TEXTURE_URLS: Record<string, string> = {
   "haar_detail_NRM.jpg": new URL("../../game_assets/models/downloaded/low-poly-spider/textures/haar_detail_NRM.jpg", import.meta.url).href,
 };
 const DRAGON_URL = new URL("../../game_assets/models/claudecraft/creatures/dragonevolved.glb", import.meta.url).href;
+const EMBER_MANTIS_URL = new URL("../../game_assets/models/original/bosses/ember-mantis-duelist/ember_mantis_duelist.glb", import.meta.url).href;
 const PARTY_MODEL_URLS: Record<MemberId, string> = {
   aelia: new URL("../../game_assets/models/claudecraft/chars/players/druid.glb", import.meta.url).href,
   brann: new URL("../../game_assets/models/claudecraft/chars/players/knight.glb", import.meta.url).href,
@@ -491,7 +492,7 @@ function BossFallback({ bossIndex }: { bossIndex: number }) {
   return (
     <mesh castShadow position={[position[0], 1.1, position[1]]}>
       <dodecahedronGeometry args={[1.1, 0]} />
-      <meshStandardMaterial color={bossId === "vexa" ? "#56306f" : bossId === "cindermaw" ? "#9d4c24" : "#7b3928"} emissive="#3a100c" emissiveIntensity={0.5} />
+      <meshStandardMaterial color={bossId === "vexa" ? "#56306f" : bossId === "cindermaw" ? "#9d4c24" : bossId === "ember-mantis-duelist" ? "#a42d18" : "#7b3928"} emissive="#3a100c" emissiveIntensity={0.5} />
     </mesh>
   );
 }
@@ -580,7 +581,7 @@ function BullBoss({ bossIndex }: { bossIndex: number }) {
   );
 }
 
-type AlternateBossKind = "vexa" | "cindermaw";
+type AlternateBossKind = "vexa" | "cindermaw" | "ember-mantis-duelist";
 
 const ALTERNATE_BOSS_CONFIG = {
   vexa: {
@@ -605,6 +606,17 @@ const ALTERNATE_BOSS_CONFIG = {
     light: "#ff8742",
     rotationOffset: 0,
   },
+  "ember-mantis-duelist": {
+    url: EMBER_MANTIS_URL,
+    scale: 0.78,
+    idle: "Idle",
+    move: "Sidestep",
+    attack: "LineSlash",
+    special: "CrossSlash",
+    death: "Death",
+    light: "#ff5a24",
+    rotationOffset: 0,
+  },
 } as const;
 
 function AlternateBoss({ kind, bossIndex }: { kind: AlternateBossKind; bossIndex: number }) {
@@ -634,6 +646,16 @@ function AlternateBoss({ kind, bossIndex }: { kind: AlternateBossKind; bossIndex
 
   const clipName = phase === "victory" || defeated
     ? config.death
+    : kind === "ember-mantis-duelist"
+      ? motionMode === "mantis_sidestep"
+        ? config.move
+        : motionMode === "mantis_line_telegraph"
+          ? config.attack
+          : motionMode === "mantis_cross_telegraph"
+            ? config.special
+            : motionMode === "mantis_recover"
+              ? "Recover"
+              : config.idle
       : motionMode === "skyfall"
         ? config.move
         : motionMode === "breath_telegraph" || motionMode === "breath_sweeping"
@@ -646,15 +668,21 @@ function AlternateBoss({ kind, bossIndex }: { kind: AlternateBossKind; bossIndex
     const next = actions[clipName];
     if (!next) return;
     for (const action of Object.values(actions)) action?.fadeOut(0.16);
-    next.reset().setEffectiveWeight(1).fadeIn(0.16).play();
+    const timeScale = kind === "ember-mantis-duelist" && motionMode === "mantis_line_telegraph"
-    if (phase === "victory" || defeated) {
+      ? 0.55
+      : kind === "ember-mantis-duelist" && motionMode === "mantis_cross_telegraph"
+        ? 0.6
+        : 1;
+    next.reset().setEffectiveWeight(1).setEffectiveTimeScale(timeScale).fadeIn(0.16).play();
+    const emberOneShot = kind === "ember-mantis-duelist" && clipName !== config.idle;
+    if (phase === "victory" || defeated || emberOneShot) {
       next.setLoop(THREE.LoopOnce, 1);
       next.clampWhenFinished = true;
     } else {
       next.setLoop(THREE.LoopRepeat, Number.POSITIVE_INFINITY);
     }
     return () => { next.fadeOut(0.16); };
-  }, [actions, clipName, defeated, phase]);
+  }, [actions, clipName, config.idle, defeated, kind, motionMode, phase]);
 
   useFrame((_, delta) => {
     if (!group.current) return;
@@ -672,6 +700,13 @@ function AlternateBoss({ kind, bossIndex }: { kind: AlternateBossKind; bossIndex
     );
     if (kind === "cindermaw" && (motion.mode === "breath_telegraph" || motion.mode === "breath_sweeping")) {
       targetAngle = motion.breathAngle;
+    } else if (kind === "ember-mantis-duelist" && (
+      motion.mode === "mantis_sidestep"
+      || motion.mode === "mantis_line_telegraph"
+      || motion.mode === "mantis_cross_telegraph"
+    )) {
+      const target = state.partyPositions[motion.chargeTargetId];
+      targetAngle = Math.atan2(target[0] - motion.position[0], target[1] - motion.position[1]);
     }
     const difference = Math.atan2(
       Math.sin(targetAngle - group.current.rotation.y),
@@ -877,7 +912,7 @@ function FxBurst({ kind, targetId }: { kind: PulseKind; targetId?: MemberId }) {
   const state = useGameStore.getState();
   const worldPosition = isBossFx ? targetBossMotion(state).position : targetId ? state.partyPositions[targetId] : [0, 0];
   const position: [number, number, number] = [worldPosition[0], 0.15, worldPosition[1]];
-  const color = kind === "boss" || kind === "debuff" || kind === "charge" || kind === "pounce" ? "#ff643c" : kind === "shield" ? "#62bdff" : kind === "purify" ? "#c39bff" : "#ffe087";
+  const color = kind === "boss" || kind === "debuff" || kind === "charge" || kind === "pounce" || kind === "slash" ? "#ff643c" : kind === "shield" ? "#62bdff" : kind === "purify" ? "#c39bff" : "#ffe087";
   useFrame((_, delta) => {
     age.current += delta;
     if (!ring.current || !material.current) return;
@@ -926,6 +961,7 @@ export function GameScene() {
 }
 
 useGLTF.preload(BULL_URL, false, true);
+useGLTF.preload(EMBER_MANTIS_URL, false, true);
 for (const modelUrl of Object.values(PARTY_MODEL_URLS)) useGLTF.preload(modelUrl, false, true);
 for (const loadout of Object.values(PARTY_WEAPON_URLS)) {
   useGLTF.preload(loadout.right, false, true);

src/components/boss/BossMechanicIndicators.tsx

@@ -8,6 +8,7 @@ import { useGameStore } from "../../game/store";
 const CHARGE_MARKERS = [0, 1, 2, 3, 4, 5, 6] as const;
 const STACK_DIRECTIONS = Array.from({ length: 8 }, (_, index) => (index / 8) * Math.PI * 2);
 const EMPTY_HAZARDS: never[] = [];
+const EMPTY_SLASH_LANES: never[] = [];
 type GameStoreState = ReturnType<typeof useGameStore.getState>;
 
 function motionAt(state: GameStoreState, bossIndex: number) {
@@ -68,6 +69,63 @@ export function ChargeLaneIndicator({ bossIndex = 0 }: { bossIndex?: number }) {
   );
 }
 
+function SlashLaneIndicator({ laneId, bossIndex }: { laneId: string; bossIndex: number }) {
+  const phase = useGameStore((state) => state.phase);
+  const motion = useGameStore((state) => motionAt(state, bossIndex));
+  const material = useRef<THREE.MeshBasicMaterial>(null);
+  const edgeMaterial = useRef<THREE.MeshBasicMaterial>(null);
+  useFrame(({ clock }) => {
+    if (!material.current || !edgeMaterial.current) return;
+    const current = motionAt(useGameStore.getState(), bossIndex);
+    const active = current?.mode === "mantis_recover";
+    material.current.opacity = active ? 0.5 : 0.14 + (Math.sin(clock.elapsedTime * 12) + 1) * 0.09;
+    edgeMaterial.current.opacity = active ? 1 : 0.62 + (Math.sin(clock.elapsedTime * 12) + 1) * 0.15;
+  });
+  const lane = motion?.slashLanes.find((candidate) => candidate.id === laneId);
+  if (!lane || phase !== "combat") return null;
+  const visible = motion.mode === "mantis_line_telegraph"
+    || motion.mode === "mantis_cross_telegraph"
+    || motion.mode === "mantis_recover";
+  if (!visible) return null;
+
+  const dx = lane.end[0] - lane.start[0];
+  const dz = lane.end[1] - lane.start[1];
+  const length = Math.hypot(dx, dz);
+  const angle = Math.atan2(dx, dz);
+  const midpoint: [number, number, number] = [
+    (lane.start[0] + lane.end[0]) * 0.5,
+    0.052,
+    (lane.start[1] + lane.end[1]) * 0.5,
+  ];
+  const active = motion.mode === "mantis_recover";
+  const color = active ? "#ffd36a" : "#ff5128";
+  return (
+    <group position={midpoint} rotation={[0, angle, 0]}>
+      <mesh rotation={[-Math.PI / 2, 0, 0]}>
+        <planeGeometry args={[lane.width, length]} />
+        <meshBasicMaterial ref={material} color={color} transparent opacity={0.22} depthWrite={false} />
+      </mesh>
+      {[-1, 1].map((side) => (
+        <mesh key={side} position={[side * lane.width * 0.5, 0.018, 0]}>
+          <boxGeometry args={[0.07, 0.03, length]} />
+          <meshBasicMaterial ref={side < 0 ? edgeMaterial : undefined} color={color} transparent opacity={0.8} depthWrite={false} />
+        </mesh>
+      ))}
+      {active && (
+        <mesh position={[0, 0.055, 0]}>
+          <boxGeometry args={[0.16, 0.08, length]} />
+          <meshBasicMaterial color="#fff0a8" transparent opacity={0.92} depthWrite={false} />
+        </mesh>
+      )}
+    </group>
+  );
+}
+
+export function SlashLaneIndicators({ bossIndex = 0 }: { bossIndex?: number }) {
+  const lanes = useGameStore((state) => motionAt(state, bossIndex)?.slashLanes ?? EMPTY_SLASH_LANES);
+  return <>{lanes.map((lane) => <SlashLaneIndicator key={lane.id} laneId={lane.id} bossIndex={bossIndex} />)}</>;
+}
+
 export function PounceStackIndicator({ bossIndex = 0 }: { bossIndex?: number }) {
   const phase = useGameStore((state) => state.phase);
   const motionMode = useGameStore((state) => motionAt(state, bossIndex)?.mode);
@@ -205,6 +263,7 @@ export function CircleHazardIndicators({ bossIndex = 0 }: { bossIndex?: number }
 
 const BOSS_MECHANIC_INDICATORS: readonly ComponentType<{ bossIndex?: number }>[] = [
   ChargeLaneIndicator,
+  SlashLaneIndicators,
   PounceStackIndicator,
   BindingWebIndicator,
   BreathConeIndicator,

src/frontend/data.test.ts

@@ -10,7 +10,8 @@ describe("game mode configuration", () => {
   it("selects a boss across the full encounter pool", () => {
     expect(selectRandomBoss(() => 0)).toBe("bulldrome");
     expect(selectRandomBoss(() => 0.34)).toBe("vexa");
-    expect(selectRandomBoss(() => 0.99)).toBe("cindermaw");
+    expect(selectRandomBoss(() => 0.7)).toBe("cindermaw");
+    expect(selectRandomBoss(() => 0.99)).toBe("ember-mantis-duelist");
   });
 
   it("selects two distinct bosses for PVE", () => {

src/frontend/data.ts

@@ -44,6 +44,17 @@ export const DEFAULT_COLLECTIONS: BossCollection[] = [
       { id: "maw-breath", name: "Bottled Breath", icon: "☀", rarity: "Mythic", count: 0 },
     ],
   },
+  {
+    bossId: "ember-mantis-duelist",
+    bossName: "Ember Mantis Duelist",
+    defeated: false,
+    drops: [
+      { id: "mantis-chitin", name: "Ember Chitin", icon: "◇", rarity: "Common", count: 0 },
+      { id: "mantis-edge", name: "Cinderblade Edge", icon: "⚔", rarity: "Uncommon", count: 0 },
+      { id: "mantis-antenna", name: "Duelist Antenna", icon: "⌁", rarity: "Rare", count: 0 },
+      { id: "mantis-core", name: "Molten Mantis Core", icon: "✦", rarity: "Mythic", count: 0 },
+    ],
+  },
 ];
 
 export const MODE_COPY: Record<GameModeId, { eyebrow: string; title: string; description: string; detail: string; status: string }> = {
@@ -58,7 +69,7 @@ export const MODE_COPY: Record<GameModeId, { eyebrow: string; title: string; des
     eyebrow: "1–4 hunters · chosen encounter",
     title: "Dungeons",
     description: "Choose a guardian, review its mechanics, and bring a prepared healing loadout into a focused encounter.",
-    detail: "Bulldrome · Vexa · Cindermaw",
+    detail: "Bulldrome · Vexa · Cindermaw · Ember Mantis",
     status: "Playable now",
   },
   "roguelike-pvp": {
@@ -118,7 +129,7 @@ export function createHunterSave(slotId: SaveSlotId, now: string, hunterName: st
       flawlessClears: 5,
       alliesSaved: 143,
       healingDone: 284_650,
-      bossKills: { Bulldrome: 12, Vexa: 0, Cindermaw: 4 },
+      bossKills: { Bulldrome: 12, Vexa: 0, Cindermaw: 4, "Ember Mantis Duelist": 0 },
     },
     collections: structuredClone(DEFAULT_COLLECTIONS),
   };

src/game/battleSimulation.test.ts

@@ -28,7 +28,10 @@ describe("full-mechanics dual-boss battle simulations", () => {
   const combinations: readonly (readonly [BossId, BossId])[] = [
     ["bulldrome", "vexa"],
     ["bulldrome", "cindermaw"],
+    ["bulldrome", "ember-mantis-duelist"],
     ["vexa", "cindermaw"],
+    ["vexa", "ember-mantis-duelist"],
+    ["cindermaw", "ember-mantis-duelist"],
   ];
 
   it.each(combinations)("party rotations defeat %s + %s", (first, second) => {

src/game/bossCatalog.ts

@@ -16,7 +16,7 @@ export interface BossDefinition {
   maxHp: number;
 }
 
-export const BOSS_ORDER: readonly BossId[] = ["bulldrome", "vexa", "cindermaw"];
+export const BOSS_ORDER: readonly BossId[] = ["bulldrome", "vexa", "cindermaw", "ember-mantis-duelist"];
 
 export const BOSS_DEFINITIONS: Record<BossId, BossDefinition> = {
   bulldrome: {
@@ -64,4 +64,19 @@ export const BOSS_DEFINITIONS: Record<BossId, BossDefinition> = {
     mechanics: ["Searing Sweep", "Skyfall"],
     maxHp: 410,
   },
+  "ember-mantis-duelist": {
+    id: "ember-mantis-duelist",
+    name: "Ember Mantis Duelist",
+    title: "The Cinderblade",
+    trial: "Trial IV · Blades in Motion",
+    icon: "⚔",
+    accent: "#ff6a2a",
+    summary: "Sidesteps across the arena before carving single and crossed slash lanes.",
+    briefing: "Track each sidestep. Clear the glowing Line Slash, then find a safe quadrant when both scythes form Cross Slash.",
+    failure: "Do not chase the duelist through a telegraph. Preserve space and move perpendicular to each ember lane.",
+    mapTitle: "The Cinderblade Court",
+    mapCopy: "Follow the mantis laterally, but cross glowing cut lanes only after the blades finish their recovery.",
+    mechanics: ["Line Slash", "Cross Slash"],
+    maxHp: 520,
+  },
 };

src/game/bossMechanics.ts

@@ -1,5 +1,6 @@
 import { BOSS_DEFINITIONS } from "./bossCatalog";
 import { advanceCindermawMechanics, createCindermawMotion, createCindermawState, upcomingCindermawMechanic } from "./bosses/cindermaw";
+import { advanceEmberMantisMechanics, createEmberMantisMotion, createEmberMantisState, upcomingEmberMantisMechanic } from "./bosses/emberMantis";
 import { createBaseMotion } from "./bosses/shared";
 import type { BossMechanicContext, BossMechanicEvent, BossMechanicResult } from "./bosses/types";
 import { advanceVexaMechanics, createVexaMotion, createVexaState, dropVexaVenomPool, upcomingVexaMechanic } from "./bosses/vexa";
@@ -39,6 +40,7 @@ const POUNCE_TARGET_ORDER: readonly MemberId[] = ["aelia", "nia", "orin", "vale"
 export function createBossState(bossId: BossId = "bulldrome"): BossState {
   if (bossId === "vexa") return createVexaState();
   if (bossId === "cindermaw") return createCindermawState();
+  if (bossId === "ember-mantis-duelist") return createEmberMantisState();
   const definition = BOSS_DEFINITIONS.bulldrome;
   return {
     id: "bulldrome",
@@ -55,6 +57,7 @@ export function createBossState(bossId: BossId = "bulldrome"): BossState {
 export function createBossMotionState(bossId: BossId = "bulldrome"): BossMotionState {
   if (bossId === "vexa") return createVexaMotion();
   if (bossId === "cindermaw") return createCindermawMotion();
+  if (bossId === "ember-mantis-duelist") return createEmberMantisMotion();
   return {
     ...createBaseMotion("bulldrome"),
     mode: "holding",
@@ -348,6 +351,7 @@ function advanceBulldromeMechanics(context: BossMechanicContext): BossMechanicRe
 export function advanceBossMechanics(context: BossMechanicContext): BossMechanicResult {
   if (context.boss.id === "vexa") return advanceVexaMechanics(context);
   if (context.boss.id === "cindermaw") return advanceCindermawMechanics(context);
+  if (context.boss.id === "ember-mantis-duelist") return advanceEmberMantisMechanics(context);
   return advanceBulldromeMechanics(context);
 }
 
@@ -371,6 +375,7 @@ export function handleBossDispel(
 export function upcomingMechanic(boss: BossState, motion: BossMotionState, time: number) {
   if (boss.id === "vexa") return upcomingVexaMechanic(boss, motion, time);
   if (boss.id === "cindermaw") return upcomingCindermawMechanic(boss, motion, time);
+  if (boss.id === "ember-mantis-duelist") return upcomingEmberMantisMechanic(boss, motion, time);
   if (motion.mode === "telegraph") {
     return { name: "Bull Charge", remaining: Math.max(0, motion.phaseEndsAt - time), cycle: BULL_CHARGE.telegraphDuration, urgent: true };
   }

src/game/bosses/emberMantis.test.ts

@@ -0,0 +1,97 @@
+import { describe, expect, it } from "vitest";
+import { freshParty } from "../data";
+import { pointToSegmentDistance } from "../geometry";
+import { evadeSlashLanesBehavior } from "../partyBehaviors";
+import type { BossMechanicContext } from "./types";
+import {
+  advanceEmberMantisMechanics,
+  createEmberMantisMotion,
+  createEmberMantisState,
+  EMBER_MANTIS_SLASH,
+} from "./emberMantis";
+
+const POSITIONS: BossMechanicContext["partyPositions"] = {
+  aelia: [0, 4.5],
+  brann: [0, 0],
+  nia: [-3, 2],
+  orin: [3, 2],
+  vale: [0, -2],
+};
+
+function context(
+  boss: ReturnType<typeof createEmberMantisState>,
+  motion: ReturnType<typeof createEmberMantisMotion>,
+  party = freshParty(),
+  time = 0,
+  delta = 0.1,
+): BossMechanicContext {
+  return {
+    boss,
+    motion,
+    party,
+    partyPositions: structuredClone(POSITIONS),
+    time,
+    delta,
+    damageMember: (member, amount) => ({ ...member, hp: Math.max(0, member.hp - amount) }),
+  };
+}
+
+describe("Ember Mantis Duelist mechanics", () => {
+  it("sidesteps, telegraphs Line Slash, then damages targets left in the lane", () => {
+    const boss = createEmberMantisState();
+    const sidestep = advanceEmberMantisMechanics(context(boss, createEmberMantisMotion(), freshParty(), 5, 0.1));
+    expect(sidestep.motion.mode).toBe("mantis_sidestep");
+    expect(sidestep.motion.chargeTargetId).toBe("nia");
+
+    const telegraph = advanceEmberMantisMechanics(context(sidestep.boss, sidestep.motion, sidestep.party, 5.6, 0.6));
+    expect(telegraph.motion.mode).toBe("mantis_line_telegraph");
+    expect(telegraph.motion.slashLanes).toHaveLength(1);
+
+    const niaBefore = telegraph.party.find((member) => member.id === "nia")!.hp;
+    const impact = advanceEmberMantisMechanics(context(telegraph.boss, telegraph.motion, telegraph.party, 6.51, 0.91));
+    expect(impact.motion.mode).toBe("mantis_recover");
+    expect(impact.motion.mechanicHitIds).toContain("nia");
+    expect(impact.party.find((member) => member.id === "nia")!.hp).toBe(niaBefore - EMBER_MANTIS_SLASH.lineDamage);
+    expect(impact.events.some((event) => event.message.includes("Line Slash"))).toBe(true);
+  });
+
+  it("alternates into two crossed slash lanes", () => {
+    const motion = {
+      ...createEmberMantisMotion(),
+      mode: "mantis_sidestep" as const,
+      mechanicCount: 1,
+      chargeTargetId: "orin" as const,
+      chargeEnd: [0, -6.6] as [number, number],
+      phaseEndsAt: 0,
+    };
+    const result = advanceEmberMantisMechanics(context(createEmberMantisState(), motion, freshParty(), 1, 0.1));
+    expect(result.motion.mode).toBe("mantis_cross_telegraph");
+    expect(result.motion.slashLanes).toHaveLength(2);
+    expect(result.motion.slashLanes[0].id).toContain("cross");
+  });
+
+  it("gives mobile allies a target outside crossed lanes", () => {
+    const motion = {
+      ...createEmberMantisMotion(),
+      mode: "mantis_sidestep" as const,
+      mechanicCount: 1,
+      chargeTargetId: "orin" as const,
+      chargeEnd: [0, -6.6] as [number, number],
+      phaseEndsAt: 0,
+    };
+    const telegraph = advanceEmberMantisMechanics(context(createEmberMantisState(), motion, freshParty(), 1, 0.1)).motion;
+    const decision = evadeSlashLanesBehavior.decide({
+      memberId: "orin",
+      current: POSITIONS.orin,
+      formationTarget: POSITIONS.orin,
+      bossMotion: telegraph,
+      partyPositions: POSITIONS,
+      time: 1,
+    });
+    expect(decision).not.toBeNull();
+    const minimumLaneDistance = Math.min(...telegraph.slashLanes.map((lane) =>
+      pointToSegmentDistance(decision!.target, lane.start, lane.end),
+    ));
+    expect(minimumLaneDistance).toBeGreaterThan(EMBER_MANTIS_SLASH.aiClearance);
+  });
+});

src/game/bosses/emberMantis.ts

@@ -0,0 +1,247 @@
+import { BOSS_DEFINITIONS } from "../bossCatalog";
+import { angleTo, moveToward, pointToSegmentDistance } from "../geometry";
+import type { BossMotionState, BossState, MemberId, SlashLane, WorldPosition } from "../types";
+import { applyMelee, chooseLivingTarget, cloneMotion, createBaseMotion, memberName } from "./shared";
+import type { BossMechanicContext, BossMechanicResult, UpcomingMechanic } from "./types";
+
+export const EMBER_MANTIS_SLASH = {
+  firstAt: 5,
+  repeatDelay: 3.4,
+  sidestepDuration: 0.55,
+  sidestepDistance: 3.8,
+  sidestepSpeed: 7.2,
+  telegraphDuration: 0.9,
+  recoverDuration: 0.7,
+  laneLength: 18,
+  lineWidth: 1.65,
+  crossWidth: 1.45,
+  lineDamage: 32,
+  crossDamage: 25,
+  crossAngle: Math.PI * 0.18,
+  staggerDuration: 0.35,
+  aiClearance: 1.35,
+  aiEvadeSpeed: 4.8,
+} as const;
+
+const TARGET_ORDER: readonly MemberId[] = ["nia", "orin", "aelia", "vale", "brann"];
+const MIN_BOSS_X = -5.8;
+const MAX_BOSS_X = 5.8;
+
+export function createEmberMantisState(): BossState {
+  const definition = BOSS_DEFINITIONS["ember-mantis-duelist"];
+  return {
+    id: definition.id,
+    name: definition.name,
+    maxHp: definition.maxHp,
+    hp: definition.maxHp,
+    nextMeleeAt: 2.2,
+    nextNovaAt: Number.POSITIVE_INFINITY,
+    nextBrandAt: Number.POSITIVE_INFINITY,
+    brandCount: 0,
+  };
+}
+
+export function createEmberMantisMotion(): BossMotionState {
+  return {
+    ...createBaseMotion("ember-mantis-duelist"),
+    position: [0, -6.6],
+    nextMechanicAt: EMBER_MANTIS_SLASH.firstAt,
+  };
+}
+
+function clampBossX(value: number) {
+  return Math.max(MIN_BOSS_X, Math.min(MAX_BOSS_X, value));
+}
+
+function createLane(
+  id: string,
+  center: WorldPosition,
+  angle: number,
+  width: number,
+  damage: number,
+): SlashLane {
+  const halfLength = EMBER_MANTIS_SLASH.laneLength * 0.5;
+  const dx = Math.sin(angle) * halfLength;
+  const dz = Math.cos(angle) * halfLength;
+  return {
+    id,
+    start: [center[0] - dx, center[1] - dz],
+    end: [center[0] + dx, center[1] + dz],
+    width,
+    damage,
+  };
+}
+
+function beginSidestep(
+  motion: BossMotionState,
+  party: BossMechanicContext["party"],
+  partyPositions: BossMechanicContext["partyPositions"],
+  time: number,
+) {
+  const targetId = chooseLivingTarget(party, TARGET_ORDER, motion.mechanicCount);
+  const direction = motion.mechanicCount % 2 === 0 ? 1 : -1;
+  let targetX = clampBossX(motion.position[0] + direction * EMBER_MANTIS_SLASH.sidestepDistance);
+  if (Math.abs(targetX - motion.position[0]) < 1) {
+    targetX = clampBossX(motion.position[0] - direction * EMBER_MANTIS_SLASH.sidestepDistance);
+  }
+  return {
+    ...motion,
+    mode: "mantis_sidestep" as const,
+    chargeTargetId: targetId,
+    chargeEnd: [targetX, motion.position[1]] as WorldPosition,
+    phaseStartedAt: time,
+    phaseEndsAt: time + EMBER_MANTIS_SLASH.sidestepDuration,
+    nextMechanicAt: Number.POSITIVE_INFINITY,
+    slashLanes: [],
+    mechanicHitIds: [],
+    pounceCenter: [partyPositions[targetId][0], partyPositions[targetId][1]] as WorldPosition,
+  };
+}
+
+function beginSlashTelegraph(
+  motion: BossMotionState,
+  partyPositions: BossMechanicContext["partyPositions"],
+  time: number,
+) {
+  const target = partyPositions[motion.chargeTargetId];
+  const aimedAngle = angleTo(motion.position, target);
+  const isCrossSlash = motion.mechanicCount % 2 === 1;
+  const slashNumber = motion.mechanicCount + 1;
+  const lanes = isCrossSlash
+    ? [
+        createLane(`cross-${slashNumber}-left`, target, aimedAngle - EMBER_MANTIS_SLASH.crossAngle, EMBER_MANTIS_SLASH.crossWidth, EMBER_MANTIS_SLASH.crossDamage),
+        createLane(`cross-${slashNumber}-right`, target, aimedAngle + EMBER_MANTIS_SLASH.crossAngle, EMBER_MANTIS_SLASH.crossWidth, EMBER_MANTIS_SLASH.crossDamage),
+      ]
+    : [createLane(`line-${slashNumber}`, target, aimedAngle, EMBER_MANTIS_SLASH.lineWidth, EMBER_MANTIS_SLASH.lineDamage)];
+
+  return {
+    ...motion,
+    mode: isCrossSlash ? "mantis_cross_telegraph" as const : "mantis_line_telegraph" as const,
+    phaseStartedAt: time,
+    phaseEndsAt: time + EMBER_MANTIS_SLASH.telegraphDuration,
+    mechanicCount: slashNumber,
+    slashLanes: lanes,
+    mechanicHitIds: [],
+  };
+}
+
+function resolveSlash(
+  motion: BossMotionState,
+  context: BossMechanicContext,
+  events: BossMechanicResult["events"],
+) {
+  const isCrossSlash = motion.mode === "mantis_cross_telegraph";
+  const hitIds: MemberId[] = [];
+  const party = context.party.map((member) => {
+    if (member.hp <= 0) return member;
+    const lane = motion.slashLanes.find((candidate) =>
+      pointToSegmentDistance(context.partyPositions[member.id], candidate.start, candidate.end) <= candidate.width * 0.5,
+    );
+    if (!lane) return member;
+    hitIds.push(member.id);
+    events.push({
+      at: context.time,
+      message: `${member.name} is caught by ${isCrossSlash ? "Cross Slash" : "Line Slash"}.`,
+      tone: "danger",
+      pulseKind: "slash",
+      targetId: member.id,
+    });
+    return {
+      ...context.damageMember(member, lane.damage, context.partyPositions[member.id], context.time),
+      knockedUntil: Math.max(member.knockedUntil, context.time + EMBER_MANTIS_SLASH.staggerDuration),
+    };
+  });
+  return { party, hitIds };
+}
+
+export function advanceEmberMantisMechanics(context: BossMechanicContext): BossMechanicResult {
+  const boss = { ...context.boss };
+  let motion = cloneMotion(context.motion);
+  let party = context.party;
+  const events: BossMechanicResult["events"] = [];
+
+  if (motion.mode === "holding") {
+    const tank = context.partyPositions.brann;
+    motion.position = moveToward(
+      motion.position,
+      [tank[0] + motion.formationOffsetX, tank[1] - 4.25],
+      2.5 * context.delta,
+    );
+    if (context.time >= motion.nextMechanicAt) {
+      motion = beginSidestep(motion, party, context.partyPositions, context.time);
+      events.push({
+        at: context.time,
+        message: `Ember Mantis sidesteps toward ${memberName(party, motion.chargeTargetId)}. Track the blades.`,
+        tone: "danger",
+        pulseKind: "slash",
+        targetId: motion.chargeTargetId,
+      });
+    }
+  } else if (motion.mode === "mantis_sidestep") {
+    motion.position = moveToward(motion.position, motion.chargeEnd, EMBER_MANTIS_SLASH.sidestepSpeed * context.delta);
+    if (context.time >= motion.phaseEndsAt) {
+      motion = beginSlashTelegraph(motion, context.partyPositions, context.time);
+      const cross = motion.mode === "mantis_cross_telegraph";
+      events.push({
+        at: context.time,
+        message: cross ? "Cross Slash! Find a safe quadrant." : "Line Slash! Clear the glowing lane.",
+        tone: "danger",
+        pulseKind: "slash",
+        targetId: motion.chargeTargetId,
+      });
+    }
+  } else if (motion.mode === "mantis_line_telegraph" || motion.mode === "mantis_cross_telegraph") {
+    if (context.time >= motion.phaseEndsAt) {
+      const resolved = resolveSlash(motion, context, events);
+      party = resolved.party;
+      motion = {
+        ...motion,
+        mode: "mantis_recover",
+        phaseStartedAt: context.time,
+        phaseEndsAt: context.time + EMBER_MANTIS_SLASH.recoverDuration,
+        mechanicHitIds: resolved.hitIds,
+      };
+    }
+  } else if (motion.mode === "mantis_recover" && context.time >= motion.phaseEndsAt) {
+    motion = {
+      ...motion,
+      mode: "holding",
+      phaseStartedAt: context.time,
+      phaseEndsAt: 0,
+      nextMechanicAt: context.time + EMBER_MANTIS_SLASH.repeatDelay,
+      slashLanes: [],
+      mechanicHitIds: [],
+    };
+  }
+
+  applyMelee(boss, motion, party, context.partyPositions, context.time, 1.9, 14, context.damageMember);
+  return { boss, motion, party, events };
+}
+
+export function upcomingEmberMantisMechanic(
+  boss: BossState,
+  motion: BossMotionState,
+  time: number,
+): UpcomingMechanic {
+  void boss;
+  if (motion.mode === "mantis_sidestep") {
+    return { name: "Duelist repositioning", remaining: Math.max(0, motion.phaseEndsAt - time), cycle: EMBER_MANTIS_SLASH.sidestepDuration, urgent: true };
+  }
+  if (motion.mode === "mantis_line_telegraph") {
+    return { name: "Line Slash — clear lane", remaining: Math.max(0, motion.phaseEndsAt - time), cycle: EMBER_MANTIS_SLASH.telegraphDuration, urgent: true };
+  }
+  if (motion.mode === "mantis_cross_telegraph") {
+    return { name: "Cross Slash — safe quadrant", remaining: Math.max(0, motion.phaseEndsAt - time), cycle: EMBER_MANTIS_SLASH.telegraphDuration, urgent: true };
+  }
+  if (motion.mode === "mantis_recover") {
+    return { name: "Cinderblade exposed", remaining: Math.max(0, motion.phaseEndsAt - time), cycle: EMBER_MANTIS_SLASH.recoverDuration, urgent: false };
+  }
+  const nextIsCross = motion.mechanicCount % 2 === 1;
+  const remaining = Math.max(0, motion.nextMechanicAt - time);
+  return {
+    name: nextIsCross ? "Cross Slash" : "Line Slash",
+    remaining,
+    cycle: EMBER_MANTIS_SLASH.repeatDelay + EMBER_MANTIS_SLASH.telegraphDuration,
+    urgent: remaining < 2.5,
+  };
+}

src/game/bosses/shared.ts

@@ -30,6 +30,7 @@ export function createBaseMotion(bossId: BossId): BossMotionState {
     breathStartAngle: 0,
     breathEndAngle: 0,
     hazards: [],
+    slashLanes: [],
   };
 }
 
@@ -50,6 +51,11 @@ export function cloneMotion(source: BossMotionState): BossMotionState {
       nextDamageAt: { ...hazard.nextDamageAt },
       hitIds: [...hazard.hitIds],
     })),
+    slashLanes: source.slashLanes.map((lane) => ({
+      ...lane,
+      start: [lane.start[0], lane.start[1]],
+      end: [lane.end[0], lane.end[1]],
+    })),
   };
 }
 

src/game/partyBehaviors.ts

@@ -1,5 +1,6 @@
 import { BULL_CHARGE } from "./bossMechanics";
 import { CINDER_BREATH } from "./bosses/cindermaw";
+import { EMBER_MANTIS_SLASH } from "./bosses/emberMantis";
 import { moveToward, pointOutsideCircle, pointOutsideLane, pointToSegmentDistance } from "./geometry";
 import type { BossMotionState, MemberId, PartyMember, WorldPosition } from "./types";
 
@@ -122,6 +123,42 @@ export const avoidBreathBehavior: PartyBehavior = {
   },
 };
 
+export const evadeSlashLanesBehavior: PartyBehavior = {
+  id: "evade-slash-lanes",
+  decide: ({ memberId, current, formationTarget, bossMotion }) => {
+    if (bossMotion.mode !== "mantis_line_telegraph" && bossMotion.mode !== "mantis_cross_telegraph") return null;
+    if (!bossMotion.slashLanes.length) return null;
+    const unsafe = (position: WorldPosition) => bossMotion.slashLanes.some((lane) =>
+      pointToSegmentDistance(position, lane.start, lane.end) < EMBER_MANTIS_SLASH.aiClearance,
+    );
+    if (!unsafe(current) && !unsafe(formationTarget)) return null;
+
+    const origin = unsafe(formationTarget) ? formationTarget : current;
+    const memberOffset = AI_MEMBER_IDS.indexOf(memberId) * (Math.PI / 4);
+    let best = current;
+    let bestScore = Number.NEGATIVE_INFINITY;
+    for (const radius of [2.2, 3.4]) {
+      for (let index = 0; index < 8; index += 1) {
+        const angle = memberOffset + (index / 8) * Math.PI * 2;
+        const candidate = clampToArena([
+          origin[0] + Math.sin(angle) * radius,
+          origin[1] + Math.cos(angle) * radius,
+        ]);
+        const laneDistance = Math.min(...bossMotion.slashLanes.map((lane) =>
+          pointToSegmentDistance(candidate, lane.start, lane.end),
+        ));
+        const travelPenalty = Math.hypot(candidate[0] - current[0], candidate[1] - current[1]) * 0.08;
+        const score = laneDistance - travelPenalty;
+        if (score > bestScore) {
+          best = candidate;
+          bestScore = score;
+        }
+      }
+    }
+    return { target: best, speed: EMBER_MANTIS_SLASH.aiEvadeSpeed };
+  },
+};
+
 export const avoidCircleHazardsBehavior: PartyBehavior = {
   id: "avoid-circle-hazards",
   decide: ({ memberId, current, formationTarget, bossMotion, time }) => {
@@ -143,7 +180,7 @@ export const avoidCircleHazardsBehavior: PartyBehavior = {
 export const maintainFormationBehavior: PartyBehavior = {
   id: "maintain-formation",
   decide: ({ formationTarget, bossMotion, memberId }) => {
-    if (!["holding", "telegraph", "tethering", "venom_cast", "skyfall"].includes(bossMotion.mode)) return null;
+    if (!["holding", "telegraph", "tethering", "venom_cast", "skyfall", "mantis_sidestep", "mantis_recover"].includes(bossMotion.mode)) return null;
     return { target: formationTarget, speed: MOVE_SPEEDS[memberId] };
   },
 };
@@ -152,6 +189,7 @@ export const DEFAULT_PARTY_BEHAVIORS: readonly PartyBehavior[] = [
   breakTetherBehavior,
   stackForPounceBehavior,
   evadeChargeBehavior,
+  evadeSlashLanesBehavior,
   avoidBreathBehavior,
   avoidCircleHazardsBehavior,
   maintainFormationBehavior,

src/game/partyCombat.test.ts

@@ -144,7 +144,10 @@ describe("dual-boss damage simulations", () => {
   const combinations: readonly (readonly [BossId, BossId])[] = [
     ["bulldrome", "vexa"],
     ["bulldrome", "cindermaw"],
+    ["bulldrome", "ember-mantis-duelist"],
     ["vexa", "cindermaw"],
+    ["vexa", "ember-mantis-duelist"],
+    ["cindermaw", "ember-mantis-duelist"],
   ];
 
   it.each(combinations)("defeats %s + %s using explicit party abilities", (first, second) => {

src/game/types.ts

@@ -1,9 +1,9 @@
 export type MemberId = "aelia" | "brann" | "nia" | "orin" | "vale";
 export type AbilityId = "mend" | "renew" | "shield" | "purify" | "radiance" | "barrier";
-export type BossId = "bulldrome" | "vexa" | "cindermaw";
+export type BossId = "bulldrome" | "vexa" | "cindermaw" | "ember-mantis-duelist";
 export type GamePhase = "briefing" | "combat" | "victory" | "defeat";
 export type BottomTab = "combat" | "map" | "pack";
-export type PulseKind = AbilityId | "boss" | "debuff" | "charge" | "pounce" | "tether" | "venom" | "breath" | "skyfall";
+export type PulseKind = AbilityId | "boss" | "debuff" | "charge" | "pounce" | "tether" | "venom" | "breath" | "skyfall" | "slash";
 export type BossMotionMode =
   | "holding"
   | "telegraph"
@@ -15,7 +15,11 @@ export type BossMotionMode =
   | "venom_cast"
   | "breath_telegraph"
   | "breath_sweeping"
-  | "skyfall";
+  | "skyfall"
+  | "mantis_sidestep"
+  | "mantis_line_telegraph"
+  | "mantis_cross_telegraph"
+  | "mantis_recover";
 export type WorldPosition = [number, number];
 
 export type CircleHazardKind = "venom_pool" | "skyfall";
@@ -34,6 +38,14 @@ export interface CircleHazard {
   hitIds: MemberId[];
 }
 
+export interface SlashLane {
+  id: string;
+  start: WorldPosition;
+  end: WorldPosition;
+  width: number;
+  damage: number;
+}
+
 export interface Debuff {
   id: string;
   name: string;
@@ -95,6 +107,7 @@ export interface BossMotionState {
   breathStartAngle: number;
   breathEndAngle: number;
   hazards: CircleHazard[];
+  slashLanes: SlashLane[];
 }
 
 export interface AbilityDefinition {