diff --git a/src/server/scripts/Spells/spell_dk.cpp b/src/server/scripts/Spells/spell_dk.cpp
index 046dd925e3..6d3c3d942e 100644
--- a/src/server/scripts/Spells/spell_dk.cpp
+++ b/src/server/scripts/Spells/spell_dk.cpp
@@ -1708,6 +1708,23 @@ class spell_dk_improved_unholy_presence : public AuraScript
     }
 };
 
+// -49220 - Impurity
+class spell_dk_impurity : public AuraScript
+{
+    PrepareAuraScript(spell_dk_impurity);
+
+    void CalculateAmount(AuraEffect const* /*aurEff*/, int32& amount, bool& /*canBeRecalculated*/)
+    {
+        if (AuraEffect* aurEff = caster->GetDummyAuraEffect(SPELLFAMILY_DEATHKNIGHT, 1986 /*Impurity IconID*/, EFFECT_0))
+            AddPct(amount, aurEff->GetAmount());
+    }
+
+    void Register() override
+    {
+        DoEffectCalcAmount += AuraEffectCalcAmountFn(spell_dk_impurity::CalculateAmount, EFFECT_0, SPELL_EFFECT_DUMMY);
+    }
+};
+
 // 50842 - Pestilence
 class spell_dk_pestilence : public SpellScript
 {