diff --git a/Maple2.File.Parser/Maple2.File.Parser.csproj b/Maple2.File.Parser/Maple2.File.Parser.csproj
index ab4ad23..5917e98 100644
--- a/Maple2.File.Parser/Maple2.File.Parser.csproj
+++ b/Maple2.File.Parser/Maple2.File.Parser.csproj
@@ -13,7 +13,7 @@
         <PackageTags>MapleStory2, File, Parser, m2d, xml</PackageTags>
         <!-- Use following lines to write the generated files to disk. -->
         <EmitCompilerGeneratedFiles Condition=" '$(Configuration)' == 'Debug' ">true</EmitCompilerGeneratedFiles>
-        <PackageVersion>2.4.33</PackageVersion>
+        <PackageVersion>2.4.34</PackageVersion>
         <TargetFramework>net8.0</TargetFramework>
         <PackageReadmeFile>README.md</PackageReadmeFile>
         <ImplicitUsings>enable</ImplicitUsings>
diff --git a/Maple2.File.Parser/ServerTableParser.cs b/Maple2.File.Parser/ServerTableParser.cs
index 2a1e101..c959bd0 100644
--- a/Maple2.File.Parser/ServerTableParser.cs
+++ b/Maple2.File.Parser/ServerTableParser.cs
@@ -44,6 +44,7 @@ public class ServerTableParser {
     private readonly XmlSerializer spawnInteractObjectSerializer;
     private readonly XmlSerializer groupSpawnSerializer;
     private readonly XmlSerializer shadowExpeditionDropSerializer;
+    private readonly XmlSerializer additionalEffectGroupSerializer;
     private readonly XmlSerializer fishSerializer;
     private readonly XmlSerializer fishingSpotSerializer;
     private readonly XmlSerializer fishLureSerializer;
@@ -93,6 +94,7 @@ public ServerTableParser(M2dReader xmlReader) {
         spawnInteractObjectSerializer = new XmlSerializer(typeof(SpawnInteractObjectRoot));
         groupSpawnSerializer = new XmlSerializer(typeof(GroupSpawnRoot));
         shadowExpeditionDropSerializer = new XmlSerializer(typeof(ShadowExpeditionDropRoot));
+        additionalEffectGroupSerializer = new XmlSerializer(typeof(AdditionalEffectGroupRoot));
         fishSerializer = new XmlSerializer(typeof(FishRoot));
         fishingSpotSerializer = new XmlSerializer(typeof(FishingSpotRoot));
         fishLureSerializer = new XmlSerializer(typeof(FishLureRoot));
@@ -524,6 +526,17 @@ public IEnumerable<ShadowExpeditionDrop> ParseShadowExpeditionDrop() {
         }
     }
 
+    public IEnumerable<(int Id, AdditionalEffectGroup Group)> ParseAdditionalEffectGroup() {
+        string xml = Sanitizer.RemoveEmpty(xmlReader.GetString(xmlReader.GetEntry("table/Server/additionalEffectGroup.xml")));
+        var reader = XmlReader.Create(new StringReader(xml));
+        var data = additionalEffectGroupSerializer.Deserialize(reader) as AdditionalEffectGroupRoot;
+        Debug.Assert(data != null);
+
+        foreach (AdditionalEffectGroup group in data.group) {
+            yield return (group.groupId, group);
+        }
+    }
+
     public IEnumerable<(int Id, Fish Fish)> ParseFish() {
         string xml = Sanitizer.RemoveEmpty(xmlReader.GetString(xmlReader.GetEntry("table/Server/fish.xml")));
         var reader = XmlReader.Create(new StringReader(xml));
diff --git a/Maple2.File.Parser/Xml/Npc/AdditionalEffect.cs b/Maple2.File.Parser/Xml/Npc/AdditionalEffect.cs
index d550322..77acf1d 100644
--- a/Maple2.File.Parser/Xml/Npc/AdditionalEffect.cs
+++ b/Maple2.File.Parser/Xml/Npc/AdditionalEffect.cs
@@ -5,7 +5,7 @@ namespace Maple2.File.Parser.Xml.Npc;
 public partial class AdditionalEffect {
     [M2dArray] public int[] codes = Array.Empty<int>();
     [M2dArray] public short[] levels = Array.Empty<short>();
-    [M2dArray(Delimiter = ':')] public string[] group = Array.Empty<string>();
+    [M2dArray] public int[] group = Array.Empty<int>();
     [M2dArray] public int[] rewardCodes = Array.Empty<int>();
     [M2dArray] public short[] rewardLevels = Array.Empty<short>();
 }
diff --git a/Maple2.File.Parser/Xml/Table/Server/AdditionalEffectGroup.cs b/Maple2.File.Parser/Xml/Table/Server/AdditionalEffectGroup.cs
new file mode 100644
index 0000000..ee868a3
--- /dev/null
+++ b/Maple2.File.Parser/Xml/Table/Server/AdditionalEffectGroup.cs
@@ -0,0 +1,22 @@
+using System.Xml.Serialization;
+using M2dXmlGenerator;
+
+namespace Maple2.File.Parser.Xml.Table.Server;
+
+// ./data/server/table/Server/additionalEffectGroup.xml
+// An npc's <additionalEffect group="G,N"> names group G and how many of its rows to roll.
+[XmlRoot("ms2")]
+public class AdditionalEffectGroupRoot {
+    [XmlElement] public List<AdditionalEffectGroup> group;
+}
+
+public partial class AdditionalEffectGroup {
+    [XmlAttribute] public int groupId;
+    [XmlElement] public List<Value> value;
+
+    // One row is one buff. Two ids are a visible effect plus its hidden driver or splash helper.
+    public partial class Value {
+        [M2dArray] public int[] effectId = Array.Empty<int>();
+        [M2dArray] public short[] effectLevel = Array.Empty<short>();
+    }
+}
diff --git a/Maple2.File.Tests/NpcParserTest.cs b/Maple2.File.Tests/NpcParserTest.cs
index 919f7dd..6bcb523 100644
--- a/Maple2.File.Tests/NpcParserTest.cs
+++ b/Maple2.File.Tests/NpcParserTest.cs
@@ -29,6 +29,22 @@ public void TestNpcParser() {
         Assert.AreEqual(7535, count);
     }
 
+    [TestMethod]
+    public void TestNpcAdditionalEffectGroup() {
+        var locale = Locale.NA;
+        Filter.Load(TestUtils.XmlReader, locale.ToString(), "Live");
+        var parser = new NpcParser(TestUtils.XmlReader, "en");
+
+        // npc 49300001 (Destroyer), ShadowExpedition: <additionalEffect codes="92900999" levels="1" group="101,2" />
+        // npc 21000001 (Orange Mushroom): group=""
+        Dictionary<int, NpcData> npcs = parser.Parse()
+            .Where(entry => entry.Id is 49300001 or 21000001)
+            .ToDictionary(entry => entry.Id, entry => entry.Data);
+        CollectionAssert.AreEqual(new[] { 92900999 }, npcs[49300001].additionalEffect.codes);
+        CollectionAssert.AreEqual(new[] { 101, 2 }, npcs[49300001].additionalEffect.group);
+        Assert.AreEqual(0, npcs[21000001].additionalEffect.group.Length);
+    }
+
     [TestMethod]
     public void TestNpcParserNew() {
         var locale = Locale.KR;
diff --git a/Maple2.File.Tests/ServerTableParserTest.cs b/Maple2.File.Tests/ServerTableParserTest.cs
index 979f80e..a037be6 100644
--- a/Maple2.File.Tests/ServerTableParserTest.cs
+++ b/Maple2.File.Tests/ServerTableParserTest.cs
@@ -289,6 +289,26 @@ public void TestShadowExpeditionDrop() {
         CollectionAssert.AreEqual(new[] { 920001002, 920006034, 920000034, 820000034 }, last.dropBoxId);
     }
 
+    [TestMethod]
+    public void TestAdditionalEffectGroup() {
+        var parser = new ServerTableParser(TestUtils.ServerReader);
+
+        Dictionary<int, AdditionalEffectGroup> groups = parser.ParseAdditionalEffectGroup()
+            .ToDictionary(entry => entry.Id, entry => entry.Group);
+        CollectionAssert.AreEquivalent(new[] { 1, 101, 999 }, groups.Keys.ToArray());
+        Assert.AreEqual(9, groups[1].value.Count);
+        Assert.AreEqual(7, groups[101].value.Count);
+        Assert.AreEqual(1, groups[999].value.Count);
+
+        // group 101, first row: <value effectId="60125001,60125002" effectLevel="1,1" />
+        CollectionAssert.AreEqual(new[] { 60125001, 60125002 }, groups[101].value[0].effectId);
+        CollectionAssert.AreEqual(new short[] { 1, 1 }, groups[101].value[0].effectLevel);
+
+        // group 1, fourth row: <value effectId="60128001" effectLevel="2" />
+        CollectionAssert.AreEqual(new[] { 60128001 }, groups[1].value[3].effectId);
+        CollectionAssert.AreEqual(new short[] { 2 }, groups[1].value[3].effectLevel);
+    }
+
     [TestMethod]
     public void TestSpawnInteractObject() {
         var parser = new ServerTableParser(TestUtils.ServerReader);