PaperMC/paper-server/nms-patches/net/minecraft/world/entity/monster/EntityIllagerIllusioner.patch

--- a/net/minecraft/world/entity/monster/EntityIllagerIllusioner.java
+++ b/net/minecraft/world/entity/monster/EntityIllagerIllusioner.java
@@ -215,7 +215,7 @@
 
         @Override
         protected void performSpellCasting() {
-            EntityIllagerIllusioner.this.addEffect(new MobEffect(MobEffects.INVISIBILITY, 1200));
+            EntityIllagerIllusioner.this.addEffect(new MobEffect(MobEffects.INVISIBILITY, 1200), org.bukkit.event.entity.EntityPotionEffectEvent.Cause.ILLUSION); // CraftBukkit
         }
 
         @Nullable
@@ -266,7 +266,7 @@
 
         @Override
         protected void performSpellCasting() {
-            EntityIllagerIllusioner.this.getTarget().addEffect(new MobEffect(MobEffects.BLINDNESS, 400), EntityIllagerIllusioner.this);
+            EntityIllagerIllusioner.this.getTarget().addEffect(new MobEffect(MobEffects.BLINDNESS, 400), EntityIllagerIllusioner.this, org.bukkit.event.entity.EntityPotionEffectEvent.Cause.ATTACK); // CraftBukkit
         }
 
         @Override