Add advantage/disadvantage rolling for initiative

Right-click or long-press the d20 button (per-combatant or Roll All)
to open a context menu with Advantage and Disadvantage options.
Normal left-click behavior is unchanged.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/web/src/App.tsx

@@ -7,6 +7,7 @@ import {
 	type Creature,
 	type CreatureId,
 	isDomainError,
+	type RollMode,
 } from "@initiative/domain";
 import {
 	useCallback,
@@ -147,12 +148,15 @@ export function App() {
 	);
 
 	const handleRollInitiative = useCallback(
-		(id: CombatantId) => {
+		(id: CombatantId, mode: RollMode = "normal") => {
+			const diceRolls: [number, ...number[]] =
+				mode === "normal" ? [rollDice()] : [rollDice(), rollDice()];
 			const result = rollInitiativeUseCase(
 				makeStore(),
 				id,
-				rollDice(),
+				diceRolls,
 				getCreature,
+				mode,
 			);
 			if (isDomainError(result)) {
 				setRollSingleSkipped(true);
@@ -165,12 +169,20 @@ export function App() {
 		[makeStore, getCreature, encounter.combatants, sidePanel.showCreature],
 	);
 
-	const handleRollAllInitiative = useCallback(() => {
-		const result = rollAllInitiativeUseCase(makeStore(), rollDice, getCreature);
+	const handleRollAllInitiative = useCallback(
+		(mode: RollMode = "normal") => {
+			const result = rollAllInitiativeUseCase(
+				makeStore(),
+				rollDice,
+				getCreature,
+				mode,
+			);
 			if (!isDomainError(result) && result.skippedNoSource > 0) {
 				setRollSkippedCount(result.skippedNoSource);
 			}
-	}, [makeStore, getCreature]);
+		},
+		[makeStore, getCreature],
+	);
 
 	const handleViewStatBlock = useCallback(
 		(result: SearchResult) => {
@@ -210,9 +222,9 @@ export function App() {
 		encounter.combatants[encounter.activeIndex]?.creatureId;
 	useEffect(() => {
 		if (activeCreatureId && sidePanel.panelView.mode === "creature") {
-			sidePanel.showCreature(activeCreatureId);
+			sidePanel.updateCreature(activeCreatureId);
 		}
-	}, [activeCreatureId, sidePanel.panelView.mode, sidePanel.showCreature]);
+	}, [activeCreatureId, sidePanel.panelView.mode, sidePanel.updateCreature]);
 
 	// Auto-scroll to the active combatant when the turn changes
 	const activeRowRef = useRef<HTMLDivElement>(null);

apps/web/src/components/action-bar.tsx

@@ -1,4 +1,4 @@
-import type { PlayerCharacter } from "@initiative/domain";
+import type { PlayerCharacter, RollMode } from "@initiative/domain";
 import {
 	Check,
 	Eye,
@@ -12,11 +12,18 @@ import {
 	Sun,
 	Users,
 } from "lucide-react";
-import React, { type RefObject, useDeferredValue, useState } from "react";
+import React, {
+	type RefObject,
+	useCallback,
+	useDeferredValue,
+	useState,
+} from "react";
 import type { SearchResult } from "../hooks/use-bestiary.js";
+import { useLongPress } from "../hooks/use-long-press.js";
 import { cn } from "../lib/utils.js";
 import { D20Icon } from "./d20-icon.js";
 import { PLAYER_COLOR_HEX, PLAYER_ICON_MAP } from "./player-icon-map";
+import { RollModeMenu } from "./roll-mode-menu.js";
 import { Button } from "./ui/button.js";
 import { Input } from "./ui/input.js";
 import { OverflowMenu, type OverflowMenuItem } from "./ui/overflow-menu.js";
@@ -41,7 +48,7 @@ interface ActionBarProps {
 	playerCharacters?: readonly PlayerCharacter[];
 	onAddFromPlayerCharacter?: (pc: PlayerCharacter) => void;
 	onManagePlayers?: () => void;
-	onRollAllInitiative?: () => void;
+	onRollAllInitiative?: (mode?: RollMode) => void;
 	showRollAllInitiative?: boolean;
 	rollAllInitiativeDisabled?: boolean;
 	onOpenSourceManager?: () => void;
@@ -479,6 +486,25 @@ export function ActionBar({
 		clearCustomFields();
 	};
 
+	const [rollAllMenuPos, setRollAllMenuPos] = useState<{
+		x: number;
+		y: number;
+	} | null>(null);
+
+	const openRollAllMenu = useCallback((x: number, y: number) => {
+		setRollAllMenuPos({ x, y });
+	}, []);
+
+	const rollAllLongPress = useLongPress(
+		useCallback(
+			(e: React.TouchEvent) => {
+				const touch = e.touches[0];
+				if (touch) openRollAllMenu(touch.clientX, touch.clientY);
+			},
+			[openRollAllMenu],
+		),
+	);
+
 	const overflowItems = buildOverflowItems({
 		onManagePlayers,
 		onOpenSourceManager,
@@ -607,18 +633,32 @@ export function ActionBar({
 					<Button type="submit">Add</Button>
 				)}
 				{showRollAllInitiative && !!onRollAllInitiative && (
+					<>
 						<Button
 							type="button"
 							size="icon"
 							variant="ghost"
 							className="text-muted-foreground hover:text-hover-action"
-						onClick={onRollAllInitiative}
+							onClick={() => onRollAllInitiative()}
+							onContextMenu={(e) => {
+								e.preventDefault();
+								openRollAllMenu(e.clientX, e.clientY);
+							}}
+							{...rollAllLongPress}
 							disabled={rollAllInitiativeDisabled}
 							title="Roll all initiative"
 							aria-label="Roll all initiative"
 						>
 							<D20Icon className="h-6 w-6" />
 						</Button>
+						{!!rollAllMenuPos && (
+							<RollModeMenu
+								position={rollAllMenuPos}
+								onSelect={(mode) => onRollAllInitiative(mode)}
+								onClose={() => setRollAllMenuPos(null)}
+							/>
+						)}
+					</>
 				)}
 				{overflowItems.length > 0 && <OverflowMenu items={overflowItems} />}
 			</form>

apps/web/src/components/combatant-row.tsx

@@ -3,9 +3,11 @@ import {
 	type ConditionId,
 	deriveHpStatus,
 	type PlayerIcon,
+	type RollMode,
 } from "@initiative/domain";
 import { Book, BookOpen, Brain, X } from "lucide-react";
 import { type Ref, useCallback, useEffect, useRef, useState } from "react";
+import { useLongPress } from "../hooks/use-long-press";
 import { cn } from "../lib/utils";
 import { AcShield } from "./ac-shield";
 import { ConditionPicker } from "./condition-picker";
@@ -13,6 +15,7 @@ import { ConditionTags } from "./condition-tags";
 import { D20Icon } from "./d20-icon";
 import { HpAdjustPopover } from "./hp-adjust-popover";
 import { PLAYER_COLOR_HEX, PLAYER_ICON_MAP } from "./player-icon-map";
+import { RollModeMenu } from "./roll-mode-menu";
 import { ConfirmButton } from "./ui/confirm-button";
 import { Input } from "./ui/input";
 
@@ -42,7 +45,7 @@ interface CombatantRowProps {
 	onToggleConcentration: (id: CombatantId) => void;
 	onShowStatBlock?: () => void;
 	isStatBlockOpen?: boolean;
-	onRollInitiative?: (id: CombatantId) => void;
+	onRollInitiative?: (id: CombatantId, mode?: RollMode) => void;
 }
 
 function EditableName({
@@ -279,11 +282,29 @@ function InitiativeDisplay({
 	combatantId: CombatantId;
 	dimmed: boolean;
 	onSetInitiative: (id: CombatantId, value: number | undefined) => void;
-	onRollInitiative?: (id: CombatantId) => void;
+	onRollInitiative?: (id: CombatantId, mode?: RollMode) => void;
 }>) {
 	const [editing, setEditing] = useState(false);
 	const [draft, setDraft] = useState(initiative?.toString() ?? "");
 	const inputRef = useRef<HTMLInputElement>(null);
+	const [menuPos, setMenuPos] = useState<{
+		x: number;
+		y: number;
+	} | null>(null);
+
+	const openMenu = useCallback((x: number, y: number) => {
+		setMenuPos({ x, y });
+	}, []);
+
+	const longPress = useLongPress(
+		useCallback(
+			(e: React.TouchEvent) => {
+				const touch = e.touches[0];
+				if (touch) openMenu(touch.clientX, touch.clientY);
+			},
+			[openMenu],
+		),
+	);
 
 	const commit = useCallback(() => {
 		if (draft === "") {
@@ -328,9 +349,15 @@ function InitiativeDisplay({
 	// Empty + bestiary creature → d20 roll button
 	if (initiative === undefined && onRollInitiative) {
 		return (
+			<>
 				<button
 					type="button"
 					onClick={() => onRollInitiative(combatantId)}
+					onContextMenu={(e) => {
+						e.preventDefault();
+						openMenu(e.clientX, e.clientY);
+					}}
+					{...longPress}
 					className={cn(
 						"flex h-7 w-full items-center justify-center text-muted-foreground transition-colors hover:text-hover-neutral",
 						dimmed && "opacity-50",
@@ -340,6 +367,14 @@ function InitiativeDisplay({
 				>
 					<D20Icon className="h-7 w-7" />
 				</button>
+				{!!menuPos && (
+					<RollModeMenu
+						position={menuPos}
+						onSelect={(mode) => onRollInitiative(combatantId, mode)}
+						onClose={() => setMenuPos(null)}
+					/>
+				)}
+			</>
 		);
 	}
 

apps/web/src/components/roll-mode-menu.tsx

@@ -0,0 +1,88 @@
+import type { RollMode } from "@initiative/domain";
+import { ChevronsDown, ChevronsUp } from "lucide-react";
+import { useEffect, useLayoutEffect, useRef, useState } from "react";
+
+interface RollModeMenuProps {
+	readonly position: { x: number; y: number };
+	readonly onSelect: (mode: RollMode) => void;
+	readonly onClose: () => void;
+}
+
+export function RollModeMenu({
+	position,
+	onSelect,
+	onClose,
+}: RollModeMenuProps) {
+	const ref = useRef<HTMLDivElement>(null);
+	const [pos, setPos] = useState<{ top: number; left: number } | null>(null);
+
+	useLayoutEffect(() => {
+		const el = ref.current;
+		if (!el) return;
+		const rect = el.getBoundingClientRect();
+		const vw = document.documentElement.clientWidth;
+		const vh = document.documentElement.clientHeight;
+
+		let left = position.x;
+		let top = position.y;
+
+		if (left + rect.width > vw) left = vw - rect.width - 8;
+		if (left < 8) left = 8;
+		if (top + rect.height > vh) top = position.y - rect.height;
+		if (top < 8) top = 8;
+
+		setPos({ top, left });
+	}, [position.x, position.y]);
+
+	useEffect(() => {
+		function handleMouseDown(e: MouseEvent) {
+			if (ref.current && !ref.current.contains(e.target as Node)) {
+				onClose();
+			}
+		}
+		function handleKeyDown(e: KeyboardEvent) {
+			if (e.key === "Escape") onClose();
+		}
+		document.addEventListener("mousedown", handleMouseDown);
+		document.addEventListener("keydown", handleKeyDown);
+		return () => {
+			document.removeEventListener("mousedown", handleMouseDown);
+			document.removeEventListener("keydown", handleKeyDown);
+		};
+	}, [onClose]);
+
+	return (
+		<div
+			ref={ref}
+			className="card-glow fixed z-50 min-w-40 rounded-lg border border-border bg-card py-1"
+			style={
+				pos
+					? { top: pos.top, left: pos.left }
+					: { visibility: "hidden" as const }
+			}
+		>
+			<button
+				type="button"
+				className="flex w-full items-center gap-2 px-3 py-1.5 text-left text-emerald-400 text-sm hover:bg-hover-neutral-bg"
+				onClick={() => {
+					onSelect("advantage");
+					onClose();
+				}}
+			>
+				<ChevronsUp className="h-4 w-4" />
+				Advantage
+			</button>
+			<button
+				type="button"
+				className="flex w-full items-center gap-2 px-3 py-1.5 text-left text-red-400 text-sm hover:bg-hover-neutral-bg"
+				onClick={() => {
+					onSelect("disadvantage");
+					onClose();
+				}}
+			>
+				<ChevronsDown className="h-4 w-4" />
+				Disadvantage
+			</button>
+		</div>
+	);
+}

apps/web/src/hooks/use-long-press.ts

@@ -0,0 +1,32 @@
+import { useCallback, useRef } from "react";
+
+const LONG_PRESS_MS = 500;
+
+export function useLongPress(onLongPress: (e: React.TouchEvent) => void) {
+	const timerRef = useRef<ReturnType<typeof setTimeout>>(undefined);
+	const firedRef = useRef(false);
+
+	const onTouchStart = useCallback(
+		(e: React.TouchEvent) => {
+			firedRef.current = false;
+			timerRef.current = setTimeout(() => {
+				firedRef.current = true;
+				onLongPress(e);
+			}, LONG_PRESS_MS);
+		},
+		[onLongPress],
+	);
+
+	const onTouchEnd = useCallback((e: React.TouchEvent) => {
+		clearTimeout(timerRef.current);
+		if (firedRef.current) {
+			e.preventDefault();
+		}
+	}, []);
+
+	const onTouchMove = useCallback(() => {
+		clearTimeout(timerRef.current);
+	}, []);
+
+	return { onTouchStart, onTouchEnd, onTouchMove };
+}

apps/web/src/hooks/use-side-panel-state.ts

@@ -19,6 +19,7 @@ interface SidePanelState {
 
 interface SidePanelActions {
 	showCreature: (creatureId: CreatureId) => void;
+	updateCreature: (creatureId: CreatureId) => void;
 	showBulkImport: () => void;
 	showSourceManager: () => void;
 	dismissPanel: () => void;
@@ -52,6 +53,10 @@ export function useSidePanelState(): SidePanelState & SidePanelActions {
 		setIsRightPanelCollapsed(false);
 	}, []);
 
+	const updateCreature = useCallback((creatureId: CreatureId) => {
+		setPanelView({ mode: "creature", creatureId });
+	}, []);
+
 	const showBulkImport = useCallback(() => {
 		setPanelView({ mode: "bulk-import" });
 		setIsRightPanelCollapsed(false);
@@ -91,6 +96,7 @@ export function useSidePanelState(): SidePanelState & SidePanelActions {
 		pinnedCreatureId,
 		isWideDesktop,
 		showCreature,
+		updateCreature,
 		showBulkImport,
 		showSourceManager,
 		dismissPanel,

packages/application/src/__tests__/roll-all-initiative-use-case.test.ts

@@ -161,6 +161,48 @@ describe("rollAllInitiativeUseCase", () => {
 		expect(store.saved).toBeNull();
 	});
 
+	it("uses higher roll with advantage", () => {
+		const enc = encounterWithCombatants([
+			{ name: "A", creatureId: "creature-a" },
+		]);
+		const store = stubEncounterStore(enc);
+		const creature = makeCreature("creature-a");
+
+		// Alternating rolls: 5, 15 → advantage picks 15
+		// Dex 14 → modifier +2, so 15 + 2 = 17
+		let call = 0;
+		const result = rollAllInitiativeUseCase(
+			store,
+			() => (++call % 2 === 1 ? 5 : 15),
+			(id) => (id === CREATURE_A ? creature : undefined),
+			"advantage",
+		);
+
+		expectSuccess(result);
+		expect(requireSaved(store.saved).combatants[0].initiative).toBe(17);
+	});
+
+	it("uses lower roll with disadvantage", () => {
+		const enc = encounterWithCombatants([
+			{ name: "A", creatureId: "creature-a" },
+		]);
+		const store = stubEncounterStore(enc);
+		const creature = makeCreature("creature-a");
+
+		// Alternating rolls: 15, 5 → disadvantage picks 5
+		// Dex 14 → modifier +2, so 5 + 2 = 7
+		let call = 0;
+		const result = rollAllInitiativeUseCase(
+			store,
+			() => (++call % 2 === 1 ? 15 : 5),
+			(id) => (id === CREATURE_A ? creature : undefined),
+			"disadvantage",
+		);
+
+		expectSuccess(result);
+		expect(requireSaved(store.saved).combatants[0].initiative).toBe(7);
+	});
+
 	it("saves encounter once at the end", () => {
 		const enc = encounterWithCombatants([
 			{ name: "A", creatureId: "creature-a" },

packages/application/src/__tests__/roll-initiative-use-case.test.ts

@@ -61,7 +61,7 @@ describe("rollInitiativeUseCase", () => {
 		const result = rollInitiativeUseCase(
 			store,
 			combatantId("unknown"),
-			10,
+			[10],
 			() => undefined,
 		);
 
@@ -80,7 +80,7 @@ describe("rollInitiativeUseCase", () => {
 		const result = rollInitiativeUseCase(
 			store,
 			combatantId("Fighter"),
-			10,
+			[10],
 			() => undefined,
 		);
 
@@ -96,7 +96,7 @@ describe("rollInitiativeUseCase", () => {
 		const result = rollInitiativeUseCase(
 			store,
 			combatantId("Goblin"),
-			10,
+			[10],
 			() => undefined,
 		);
 
@@ -116,7 +116,7 @@ describe("rollInitiativeUseCase", () => {
 		const result = rollInitiativeUseCase(
 			store,
 			combatantId("Goblin"),
-			10,
+			[10],
 			(id) => (id === GOBLIN_ID ? creature : undefined),
 		);
 
@@ -124,6 +124,42 @@ describe("rollInitiativeUseCase", () => {
 		expect(requireSaved(store.saved).combatants[0].initiative).toBe(12);
 	});
 
+	it("uses higher roll with advantage", () => {
+		const creature = makeCreature();
+		const enc = encounterWithCreatureLink("Goblin", GOBLIN_ID);
+		const store = stubEncounterStore(enc);
+
+		// Dex 14 -> modifier +2, advantage picks max(5, 15) = 15, 15 + 2 = 17
+		const result = rollInitiativeUseCase(
+			store,
+			combatantId("Goblin"),
+			[5, 15],
+			(id) => (id === GOBLIN_ID ? creature : undefined),
+			"advantage",
+		);
+
+		expect(isDomainError(result)).toBe(false);
+		expect(requireSaved(store.saved).combatants[0].initiative).toBe(17);
+	});
+
+	it("uses lower roll with disadvantage", () => {
+		const creature = makeCreature();
+		const enc = encounterWithCreatureLink("Goblin", GOBLIN_ID);
+		const store = stubEncounterStore(enc);
+
+		// Dex 14 -> modifier +2, disadvantage picks min(5, 15) = 5, 5 + 2 = 7
+		const result = rollInitiativeUseCase(
+			store,
+			combatantId("Goblin"),
+			[5, 15],
+			(id) => (id === GOBLIN_ID ? creature : undefined),
+			"disadvantage",
+		);
+
+		expect(isDomainError(result)).toBe(false);
+		expect(requireSaved(store.saved).combatants[0].initiative).toBe(7);
+	});
+
 	it("applies initiative proficiency bonus correctly", () => {
 		// CR 5 -> PB 3, dex 16 -> mod +3, initiativeProficiency 1
 		// modifier = 3 + 1*3 = 6, roll 8 + 6 = 14
@@ -145,7 +181,7 @@ describe("rollInitiativeUseCase", () => {
 		const result = rollInitiativeUseCase(
 			store,
 			combatantId("Monster"),
-			8,
+			[8],
 			(id) => (id === GOBLIN_ID ? creature : undefined),
 		);
 

packages/application/src/roll-all-initiative-use-case.ts

@@ -5,7 +5,9 @@ import {
 	type DomainError,
 	type DomainEvent,
 	isDomainError,
+	type RollMode,
 	rollInitiative,
+	selectRoll,
 	setInitiative,
 } from "@initiative/domain";
 import type { EncounterStore } from "./ports.js";
@@ -19,6 +21,7 @@ export function rollAllInitiativeUseCase(
 	store: EncounterStore,
 	rollDice: () => number,
 	getCreature: (id: CreatureId) => Creature | undefined,
+	mode: RollMode = "normal",
 ): RollAllResult | DomainError {
 	let encounter = store.get();
 	const allEvents: DomainEvent[] = [];
@@ -39,7 +42,10 @@ export function rollAllInitiativeUseCase(
 			cr: creature.cr,
 			initiativeProficiency: creature.initiativeProficiency,
 		});
-		const value = rollInitiative(rollDice(), modifier);
+		const roll1 = rollDice();
+		const effectiveRoll =
+			mode === "normal" ? roll1 : selectRoll(roll1, rollDice(), mode);
+		const value = rollInitiative(effectiveRoll, modifier);
 
 		if (isDomainError(value)) {
 			return value;

packages/application/src/roll-initiative-use-case.ts

@@ -6,7 +6,9 @@ import {
 	type DomainError,
 	type DomainEvent,
 	isDomainError,
+	type RollMode,
 	rollInitiative,
+	selectRoll,
 	setInitiative,
 } from "@initiative/domain";
 import type { EncounterStore } from "./ports.js";
@@ -14,8 +16,9 @@ import type { EncounterStore } from "./ports.js";
 export function rollInitiativeUseCase(
 	store: EncounterStore,
 	combatantId: CombatantId,
-	diceRoll: number,
+	diceRolls: readonly [number, ...number[]],
 	getCreature: (id: CreatureId) => Creature | undefined,
+	mode: RollMode = "normal",
 ): DomainEvent[] | DomainError {
 	const encounter = store.get();
 	const combatant = encounter.combatants.find((c) => c.id === combatantId);
@@ -50,7 +53,11 @@ export function rollInitiativeUseCase(
 		cr: creature.cr,
 		initiativeProficiency: creature.initiativeProficiency,
 	});
-	const value = rollInitiative(diceRoll, modifier);
+	const effectiveRoll =
+		mode === "normal"
+			? diceRolls[0]
+			: selectRoll(diceRolls[0], diceRolls[1] ?? diceRolls[0], mode);
+	const value = rollInitiative(effectiveRoll, modifier);
 
 	if (isDomainError(value)) {
 		return value;

packages/domain/src/__tests__/roll-initiative.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, it } from "vitest";
-import { rollInitiative } from "../roll-initiative.js";
+import { rollInitiative, selectRoll } from "../roll-initiative.js";
 import { isDomainError } from "../types.js";
 import { expectDomainError } from "./test-helpers.js";
 
@@ -63,3 +63,31 @@ describe("rollInitiative", () => {
 		});
 	});
 });
+
+describe("selectRoll", () => {
+	it("normal mode returns the first roll", () => {
+		expect(selectRoll(8, 15, "normal")).toBe(8);
+	});
+
+	it("advantage returns the higher roll", () => {
+		expect(selectRoll(8, 15, "advantage")).toBe(15);
+	});
+
+	it("advantage returns the higher roll (reversed)", () => {
+		expect(selectRoll(15, 8, "advantage")).toBe(15);
+	});
+
+	it("disadvantage returns the lower roll", () => {
+		expect(selectRoll(8, 15, "disadvantage")).toBe(8);
+	});
+
+	it("disadvantage returns the lower roll (reversed)", () => {
+		expect(selectRoll(15, 8, "disadvantage")).toBe(8);
+	});
+
+	it("equal rolls return the same value for all modes", () => {
+		expect(selectRoll(12, 12, "normal")).toBe(12);
+		expect(selectRoll(12, 12, "advantage")).toBe(12);
+		expect(selectRoll(12, 12, "disadvantage")).toBe(12);
+	});
+});

packages/domain/src/index.ts

@@ -84,7 +84,11 @@ export {
 	removeCombatant,
 } from "./remove-combatant.js";
 export { retreatTurn } from "./retreat-turn.js";
-export { rollInitiative } from "./roll-initiative.js";
+export {
+	type RollMode,
+	rollInitiative,
+	selectRoll,
+} from "./roll-initiative.js";
 export { type SetAcSuccess, setAc } from "./set-ac.js";
 export { type SetHpSuccess, setHp } from "./set-hp.js";
 export {

packages/domain/src/roll-initiative.ts

@@ -1,5 +1,21 @@
 import type { DomainError } from "./types.js";
 
+export type RollMode = "normal" | "advantage" | "disadvantage";
+
+/**
+ * Selects the effective roll from two dice values based on the roll mode.
+ * Advantage takes the higher, disadvantage takes the lower.
+ */
+export function selectRoll(
+	roll1: number,
+	roll2: number,
+	mode: RollMode,
+): number {
+	if (mode === "advantage") return Math.max(roll1, roll2);
+	if (mode === "disadvantage") return Math.min(roll1, roll2);
+	return roll1;
+}
+
 /**
  * Pure function that computes initiative from a resolved dice roll and modifier.
  * The dice roll must be an integer in [1, 20].