diff --git a/src/battle-scene.ts b/src/battle-scene.ts
index 397663d0a60..fe17d349903 100644
--- a/src/battle-scene.ts
+++ b/src/battle-scene.ts
@@ -30,7 +30,6 @@ import {
   HealingBoosterModifier,
   MultipleParticipantExpBonusModifier,
   PersistentModifier,
-  PokemonHeldItemModifier,
   PokemonHpRestoreModifier,
   RememberMoveModifier,
 } from "./modifier/modifier";
@@ -150,7 +149,6 @@ import {
 import { MysteryEncounterSaveData } from "#app/data/mystery-encounters/mystery-encounter-save-data";
 import { MysteryEncounterType } from "#enums/mystery-encounter-type";
 import { MysteryEncounterTier } from "#enums/mystery-encounter-tier";
-import type HeldModifierConfig from "#app/@types/held-modifier-config";
 import { MysteryEncounterMode } from "#enums/mystery-encounter-mode";
 import { ExpGainsSpeed } from "#enums/exp-gains-speed";
 import { BattlerTagType } from "#enums/battler-tag-type";
@@ -167,6 +165,7 @@ import { allHeldItems, applyHeldItems } from "./items/all-held-items";
 import { ITEM_EFFECT } from "./items/held-item";
 import { PhaseManager } from "./phase-manager";
 import { HeldItemId } from "#enums/held-item-id";
+import type { HeldItemPropertyMap } from "./field/pokemon-held-item-manager";
 
 const DEBUG_RNG = false;
 
@@ -2088,9 +2087,7 @@ export default class BattleScene extends SceneBase {
       enemy.getSpeciesForm().getBaseExp() *
       (enemy.level / this.getMaxExpLevel()) *
       ((enemy.ivs.reduce((iv: number, total: number) => (total += iv), 0) / 93) * 0.2 + 0.8);
-    this.findModifiers(m => m instanceof PokemonHeldItemModifier && m.pokemonId === enemy.id, false).map(
-      m => (scoreIncrease *= (m as PokemonHeldItemModifier).getScoreMultiplier()),
-    );
+    enemy.getHeldItems().map(m => (scoreIncrease *= allHeldItems[m].getScoreMultiplier()));
     if (enemy.isBoss()) {
       scoreIncrease *= Math.sqrt(enemy.bossSegments);
     }
@@ -2806,7 +2803,7 @@ export default class BattleScene extends SceneBase {
     return countTaken > 0;
   }
 
-  generateEnemyModifiers(heldModifiersConfigs?: HeldModifierConfig[][]): Promise<void> {
+  generateEnemyModifiers(heldItemConfigs?: HeldItemPropertyMap[]): Promise<void> {
     return new Promise(resolve => {
       if (this.currentBattle.battleSpec === BattleSpec.FINAL_BOSS) {
         return resolve();
@@ -2828,19 +2825,8 @@ export default class BattleScene extends SceneBase {
       }
 
       party.forEach((enemyPokemon: EnemyPokemon, i: number) => {
-        if (heldModifiersConfigs && i < heldModifiersConfigs.length && heldModifiersConfigs[i]) {
-          for (const mt of heldModifiersConfigs[i]) {
-            let modifier: PokemonHeldItemModifier;
-            if (mt.modifier instanceof PokemonHeldItemModifierType) {
-              modifier = mt.modifier.newModifier(enemyPokemon);
-            } else {
-              modifier = mt.modifier as PokemonHeldItemModifier;
-              modifier.pokemonId = enemyPokemon.id;
-            }
-            modifier.stackCount = mt.stackCount ?? 1;
-            modifier.isTransferable = mt.isTransferable ?? modifier.isTransferable;
-            this.addEnemyModifier(modifier, true);
-          }
+        if (heldItemConfigs && i < heldItemConfigs.length && heldItemConfigs[i]) {
+          enemyPokemon.heldItemManager.overrideItems(heldItemConfigs[i]);
         } else {
           const isBoss =
             enemyPokemon.isBoss() ||
diff --git a/src/data/mystery-encounters/encounters/dark-deal-encounter.ts b/src/data/mystery-encounters/encounters/dark-deal-encounter.ts
index 6474df3570e..451f62765b0 100644
--- a/src/data/mystery-encounters/encounters/dark-deal-encounter.ts
+++ b/src/data/mystery-encounters/encounters/dark-deal-encounter.ts
@@ -16,10 +16,9 @@ import {
 } from "#app/data/mystery-encounters/utils/encounter-pokemon-utils";
 import { MysteryEncounterTier } from "#enums/mystery-encounter-tier";
 import { MysteryEncounterOptionMode } from "#enums/mystery-encounter-option-mode";
-import type { PokemonHeldItemModifier } from "#app/modifier/modifier";
-import { PokemonFormChangeItemModifier } from "#app/modifier/modifier";
 import { CLASSIC_MODE_MYSTERY_ENCOUNTER_WAVES } from "#app/constants";
 import { Challenges } from "#enums/challenges";
+import type { HeldItemPropertyMap } from "#app/field/pokemon-held-item-manager";
 
 /** i18n namespace for encounter */
 const namespace = "mysteryEncounters/darkDeal";
@@ -149,7 +148,7 @@ export const DarkDealEncounter: MysteryEncounter = MysteryEncounterBuilder.withE
         const removedPokemon = getRandomPlayerPokemon(true, false, true);
 
         // Get all the pokemon's held items
-        const modifiers = removedPokemon.getHeldItems().filter(m => !(m instanceof PokemonFormChangeItemModifier));
+        const itemConfig = removedPokemon.heldItemManager.heldItems;
         globalScene.removePokemonFromPlayerParty(removedPokemon);
 
         const encounter = globalScene.currentBattle.mysteryEncounter!;
@@ -158,7 +157,7 @@ export const DarkDealEncounter: MysteryEncounter = MysteryEncounterBuilder.withE
         // Store removed pokemon types
         encounter.misc = {
           removedTypes: removedPokemon.getTypes(),
-          modifiers,
+          itemConfig: itemConfig,
         };
       })
       .withOptionPhase(async () => {
@@ -176,7 +175,7 @@ export const DarkDealEncounter: MysteryEncounter = MysteryEncounterBuilder.withE
           bossTypes = singleTypeChallenges.map(c => (c.value - 1) as PokemonType);
         }
 
-        const bossModifiers: PokemonHeldItemModifier[] = encounter.misc.modifiers;
+        const bossItemConfig: HeldItemPropertyMap = encounter.misc.itemConfig;
         // Starter egg tier, 35/50/10/5 %odds for tiers 6/7/8/9+
         const roll = randSeedInt(100);
         const starterTier: number | [number, number] = roll >= 65 ? 6 : roll >= 15 ? 7 : roll >= 5 ? 8 : [9, 10];
@@ -184,12 +183,7 @@ export const DarkDealEncounter: MysteryEncounter = MysteryEncounterBuilder.withE
         const pokemonConfig: EnemyPokemonConfig = {
           species: bossSpecies,
           isBoss: true,
-          modifierConfigs: bossModifiers.map(m => {
-            return {
-              modifier: m,
-              stackCount: m.getStackCount(),
-            };
-          }),
+          heldItemConfig: bossItemConfig,
         };
         if (!isNullOrUndefined(bossSpecies.forms) && bossSpecies.forms.length > 0) {
           pokemonConfig.formIndex = 0;
diff --git a/src/data/mystery-encounters/utils/encounter-phase-utils.ts b/src/data/mystery-encounters/utils/encounter-phase-utils.ts
index 69984229681..8edbf78983b 100644
--- a/src/data/mystery-encounters/utils/encounter-phase-utils.ts
+++ b/src/data/mystery-encounters/utils/encounter-phase-utils.ts
@@ -48,7 +48,6 @@ import type PokemonSpecies from "#app/data/pokemon-species";
 import type { IEggOptions } from "#app/data/egg";
 import { Egg } from "#app/data/egg";
 import type { CustomPokemonData } from "#app/data/custom-pokemon-data";
-import type HeldModifierConfig from "#app/@types/held-modifier-config";
 import type { Variant } from "#app/sprites/variant";
 import { StatusEffect } from "#enums/status-effect";
 import { globalScene } from "#app/global-scene";
@@ -57,6 +56,7 @@ import { PokemonType } from "#enums/pokemon-type";
 import { getNatureName } from "#app/data/nature";
 import { getPokemonNameWithAffix } from "#app/messages";
 import { timedEventManager } from "#app/global-event-manager";
+import type { HeldItemPropertyMap } from "#app/field/pokemon-held-item-manager";
 
 /**
  * Animates exclamation sprite over trainer's head at start of encounter
@@ -106,7 +106,7 @@ export interface EnemyPokemonConfig {
   /** Can set just the status, or pass a timer on the status turns */
   status?: StatusEffect | [StatusEffect, number];
   mysteryEncounterBattleEffects?: (pokemon: Pokemon) => void;
-  modifierConfigs?: HeldModifierConfig[];
+  heldItemConfig?: HeldItemPropertyMap;
   tags?: BattlerTagType[];
   dataSource?: PokemonData;
   tera?: PokemonType;
@@ -438,8 +438,8 @@ export async function initBattleWithEnemyConfig(partyConfig: EnemyPartyConfig):
       battle.battleType === BattleType.TRAINER ? ModifierPoolType.TRAINER : ModifierPoolType.WILD,
     );
     const customModifierTypes = partyConfig?.pokemonConfigs
-      ?.filter(config => config?.modifierConfigs)
-      .map(config => config.modifierConfigs!);
+      ?.filter(config => config?.heldItemConfig)
+      .map(config => config.heldItemConfig!);
     globalScene.generateEnemyModifiers(customModifierTypes);
   }
 }