diff --git a/.Lib9c.Tests/Model/State/CollectionStateTest.cs b/.Lib9c.Tests/Model/State/CollectionStateTest.cs
index b02dc0cf4b..53c62cbd9a 100644
--- a/.Lib9c.Tests/Model/State/CollectionStateTest.cs
+++ b/.Lib9c.Tests/Model/State/CollectionStateTest.cs
@@ -2,8 +2,6 @@ namespace Lib9c.Tests.Model.State
 {
     using System.Collections.Generic;
     using Bencodex.Types;
-    using Libplanet.Crypto;
-    using Nekoyume.Action;
     using Nekoyume.Model.State;
     using Xunit;
 
@@ -14,20 +12,23 @@ public void Bencoded()
         {
             var state = new CollectionState
             {
-                Ids = new List<int>
+                Ids = new SortedSet<int>
                 {
                     1,
+                    3,
+                    1,
+                    2,
                     2,
                 },
             };
 
             var serialized = state.Bencoded;
             var expected = List.Empty
-                .Add(List.Empty.Add(1).Add(2));
+                .Add(List.Empty.Add(1).Add(2).Add(3));
             Assert.Equal(expected, serialized);
 
             var deserialized = new CollectionState(serialized);
-            Assert.Equal(state.Ids, deserialized.Ids);
+            Assert.Equal(new SortedSet<int> { 1, 2, 3, }, deserialized.Ids);
         }
     }
 }
diff --git a/.Lib9c.Tests/Module/CollectionModuleTest.cs b/.Lib9c.Tests/Module/CollectionModuleTest.cs
index a996886239..fe3e7c5cc5 100644
--- a/.Lib9c.Tests/Module/CollectionModuleTest.cs
+++ b/.Lib9c.Tests/Module/CollectionModuleTest.cs
@@ -22,7 +22,7 @@ public void CollectionState()
 
             var state = new CollectionState
             {
-                Ids = new List<int>
+                Ids = new SortedSet<int>
                 {
                     1,
                 },
@@ -47,7 +47,7 @@ public void CollectionStates()
 
             var state = new CollectionState
             {
-                Ids = new List<int>
+                Ids = new SortedSet<int>
                 {
                     1,
                 },
diff --git a/Lib9c/Action/BattleArena.cs b/Lib9c/Action/BattleArena.cs
index b7f958979f..79f00cf2cc 100644
--- a/Lib9c/Action/BattleArena.cs
+++ b/Lib9c/Action/BattleArena.cs
@@ -397,11 +397,7 @@ public override IWorld Execute(IActionContext context)
                 foreach (var (address, state) in collectionStates)
 #pragma warning restore LAA1002
                 {
-                    var modifier = modifiers[address];
-                    foreach (var collectionId in state.Ids)
-                    {
-                        modifier.AddRange(collectionSheet[collectionId].StatModifiers);
-                    }
+                    modifiers[address] = state.GetModifiers(collectionSheet);
                 }
             }
             for (var i = 0; i < ticket; i++)
diff --git a/Lib9c/Action/EventDungeonBattle.cs b/Lib9c/Action/EventDungeonBattle.cs
index 8e75818e83..f2be6660e6 100644
--- a/Lib9c/Action/EventDungeonBattle.cs
+++ b/Lib9c/Action/EventDungeonBattle.cs
@@ -341,10 +341,7 @@ is Bencodex.Types.List serializedEventDungeonInfoList
             if (collectionExist)
             {
                 var collectionSheet = sheets.GetSheet<CollectionSheet>();
-                foreach (var collectionId in collectionState.Ids)
-                {
-                    collectionModifiers.AddRange(collectionSheet[collectionId].StatModifiers);
-                }
+                collectionModifiers = collectionState.GetModifiers(collectionSheet);
             }
 
             var deBuffLimitSheet = sheets.GetSheet<DeBuffLimitSheet>();
diff --git a/Lib9c/Action/HackAndSlash.cs b/Lib9c/Action/HackAndSlash.cs
index b91cecc313..ea621a7809 100644
--- a/Lib9c/Action/HackAndSlash.cs
+++ b/Lib9c/Action/HackAndSlash.cs
@@ -473,10 +473,7 @@ public IWorld Execute(
             if (collectionExist)
             {
                 var collectionSheet = sheets.GetSheet<CollectionSheet>();
-                foreach (var collectionId in collectionState.Ids)
-                {
-                    collectionModifiers.AddRange(collectionSheet[collectionId].StatModifiers);
-                }
+                collectionModifiers = collectionState.GetModifiers(collectionSheet);
             }
 
             var deBuffLimitSheet = sheets.GetSheet<DeBuffLimitSheet>();
diff --git a/Lib9c/Action/HackAndSlashSweep.cs b/Lib9c/Action/HackAndSlashSweep.cs
index 17e9e8a638..6d5707f46b 100644
--- a/Lib9c/Action/HackAndSlashSweep.cs
+++ b/Lib9c/Action/HackAndSlashSweep.cs
@@ -256,10 +256,7 @@ public override IWorld Execute(IActionContext context)
             if (collectionExist)
             {
                 var collectionSheet = sheets.GetSheet<CollectionSheet>();
-                foreach (var collectionId in collectionState.Ids)
-                {
-                    collectionModifiers.AddRange(collectionSheet[collectionId].StatModifiers);
-                }
+                collectionModifiers = collectionState.GetModifiers(collectionSheet);
             }
 
             var costumeStatSheet = sheets.GetSheet<CostumeStatSheet>();
diff --git a/Lib9c/Action/Raid.cs b/Lib9c/Action/Raid.cs
index 8c742a96bd..a86a6201ad 100644
--- a/Lib9c/Action/Raid.cs
+++ b/Lib9c/Action/Raid.cs
@@ -217,10 +217,7 @@ public override IWorld Execute(IActionContext context)
             if (collectionExist)
             {
                 var collectionSheet = sheets.GetSheet<CollectionSheet>();
-                foreach (var collectionId in collectionState.Ids)
-                {
-                    collectionModifiers.AddRange(collectionSheet[collectionId].StatModifiers);
-                }
+                collectionModifiers = collectionState.GetModifiers(collectionSheet);
             }
             // Simulate.
             var random = context.GetRandom();
diff --git a/Lib9c/Model/State/CollectionState.cs b/Lib9c/Model/State/CollectionState.cs
index b62af1ab83..1458e83bc4 100644
--- a/Lib9c/Model/State/CollectionState.cs
+++ b/Lib9c/Model/State/CollectionState.cs
@@ -1,6 +1,8 @@
 using System.Collections.Generic;
 using Bencodex;
 using Bencodex.Types;
+using Nekoyume.Model.Stat;
+using Nekoyume.TableData;
 
 namespace Nekoyume.Model.State
 {
@@ -9,7 +11,7 @@ namespace Nekoyume.Model.State
     /// </summary>
     public class CollectionState : IBencodable
     {
-        public List<int> Ids = new();
+        public SortedSet<int> Ids = new();
 
         public CollectionState()
         {
@@ -29,5 +31,16 @@ public CollectionState(IValue bencoded) : this((List)bencoded)
         }
 
         public IValue Bencoded => List.Empty.Add(new List(Ids));
+
+        public List<StatModifier> GetModifiers(CollectionSheet collectionSheet)
+        {
+            var collectionModifiers = new List<StatModifier>();
+            foreach (var collectionId in Ids)
+            {
+                collectionModifiers.AddRange(collectionSheet[collectionId].StatModifiers);
+            }
+
+            return collectionModifiers;
+        }
     }
 }