diff --git a/src/game/engine/stat-list.ts b/src/game/engine/stat-list.ts
index fcda6e4..47c5624 100644
--- a/src/game/engine/stat-list.ts
+++ b/src/game/engine/stat-list.ts
@@ -76,6 +76,14 @@ export class UnitStatList {
     this.baseStats.set(key, Math.trunc(value))
   }
 
+  addStat(statNameOrId: string | number, delta: number): void {
+    const key = this.normalizeStatKey(statNameOrId)
+    if (key === 'item_allskills') {
+      this.allSkillsBonus += Math.trunc(delta)
+    }
+    this.baseStats.set(key, (this.baseStats.get(key) ?? 0) + Math.trunc(delta))
+  }
+
   getBaseStat(statNameOrId: string | number): number {
     const key = this.normalizeStatKey(statNameOrId)
     return this.baseStats.get(key) ?? 0