diff --git a/Assets/Scripts/Attribute.cs b/Assets/Scripts/Attribute.cs
index 9d2ac95..222652f 100644
--- a/Assets/Scripts/Attribute.cs
+++ b/Assets/Scripts/Attribute.cs
@@ -5,25 +5,16 @@ using UnityEngine;
 public class Attribute : ScriptableObject
 {
     public long Base { get; set; }
-    public long BaseBonus { get; set; }
-    public long PermyriadBonus { get; set; }
-    public long FlatBonus { get; set; }
-
-    public long Value => Calc(Base, BaseBonus, PermyriadBonus, FlatBonus);
 
     /// <summary>
     /// Calculates the stat value with accumulated buff and debuff modifiers.
     /// </summary>
-    /// <param name="baseValue">Base value.</param>
-    /// <param name="baseBonus">Additive bonus applied before multiplicative scaling.</param>
-    /// <param name="permyriadBonus">Multiplicative scaling in hundredths of a percent. E.g., 625 permyriad corresponds to 6.25%.</param>
-    /// <param name="flatBonus">Additive bonus applied after multiplicative scaling.</param>
     /// <returns>(base + baseBonus) * (100% + permyriadBonus) + flatBonus, bounded below by 0.</returns>
-    public static long Calc(long baseValue, long baseBonus, long permyriadBonus, long flatBonus)
+    public long Calc(EffectSO effect)
     {
-        var r = baseValue + baseBonus;
-        var m = permyriadBonus + 10000;
-        r = r * (m / 10000) + (r / 10000) * (m % 10000) + flatBonus;
+        var r = Base + effect.Base;
+        var m = effect.Permyriad + 10000;
+        r = r * (m / 10000) + (r / 10000) * (m % 10000) + effect.Flat;
         if (r <= 0)
         {
             return 0;
diff --git a/Assets/Scripts/EffectSO.cs b/Assets/Scripts/EffectSO.cs
new file mode 100644
index 0000000..cd978c5
--- /dev/null
+++ b/Assets/Scripts/EffectSO.cs
@@ -0,0 +1,45 @@
+using UnityEngine;
+
+[CreateAssetMenu(fileName = "StatEffect", menuName = "Stat Effect")]
+public class EffectSO : ScriptableObject
+{
+    /// <summary>
+    /// Additive change applied before multiplicative scaling.
+    /// </summary>
+    public long Base { get; private set; }
+    /// <summary>
+    /// Multiplicative scaling in units of hundredth of a percent.
+    /// E.g., 625 permyriad is 6.25%.
+    /// </summary>
+    public long Permyriad { get; private set; }
+    /// <summary>
+    /// Additive change applied after multiplicative scaling.
+    /// </summary>
+    public long Flat { get; private set; }
+
+    /// <summary>
+    /// Create a new attribute effect instance.
+    /// </summary>
+    /// <param name="baseBonus"></param>
+    /// <param name="permyriad"></param>
+    /// <param name="flat"></param>
+    /// <returns></returns>
+    public static EffectSO New(long baseBonus = 0, long permyriad = 0, long flat = 0)
+    {
+        var effect = ScriptableObject.CreateInstance<EffectSO>();
+        effect.Base = baseBonus;
+        effect.Permyriad = permyriad;
+        effect.Flat = flat;
+        return effect;
+    }
+
+    /// <summary>
+    /// Create a new EffectSO from a percentage.
+    /// </summary>
+    /// <param name="p">Percentage. E.g., 6.25f results in a Permyriad of 625.</param>
+    /// <returns>Effect with the given percentage.</returns>
+    public static EffectSO FromPercent(float p)
+    {
+        return New(permyriad: (long)(p * 100));
+    }
+}
diff --git a/Assets/Scripts/EffectSO.cs.meta b/Assets/Scripts/EffectSO.cs.meta
new file mode 100644
index 0000000..a39567b
--- /dev/null
+++ b/Assets/Scripts/EffectSO.cs.meta
@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 494a21c06960ec442a7a6806f8aefedb
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 
diff --git a/Assets/Tests/AttributeTest.cs b/Assets/Tests/AttributeTest.cs
index f4b216c..e240b88 100644
--- a/Assets/Tests/AttributeTest.cs
+++ b/Assets/Tests/AttributeTest.cs
@@ -19,9 +19,7 @@ public class AttributeTest
     {
         var attr = ScriptableObject.CreateInstance<Attribute>();
         attr.Base = startStat;
-        attr.BaseBonus = baseBonus;
-        attr.PermyriadBonus = permyriadBonus;
-        attr.FlatBonus = flatBonus;
-        return attr.Value;
+        var effect = EffectSO.New(baseBonus, permyriadBonus, flatBonus);
+        return attr.Calc(effect);
     }
 }