Hello, few weeks ago I learnt about a simple way to disguise entities/players: 1. Set the id of the disguise (entity which another entity will be disgusied as) to the id of the disguising entity (that will make the disguise do everything the disguised does) 2. Remove the disguising entity using packets. Ok, now to my problem: I've decided to use the thing above to make NPCs that have health, can be punched and can attack you (basically disguising zombie villager as player). The problem is that whenever those disguised zombie villagers try to attack a player, the player's client crashes. This is the client error: Code (Text): Description: Rendering entity in world java.lang.ClassCastException: java.lang.Boolean cannot be cast to java.lang.Byte at aog.cS(SourceFile:2159) at dco.d(SourceFile:99) at dco.a(SourceFile:68) at dco.a(SourceFile:30) at cyo.a(RenderManager.java:434) at cyo.a(RenderManager.java:414) at cue.a(RenderGlobal.java:881) at cty.b(EntityRenderer.java:1394) at cty.a(EntityRenderer.java:1217) at cty.a(EntityRenderer.java:979) at cft.c(SourceFile:850) at cft.a(SourceFile:395) at net.minecraft.client.main.Main.main(SourceFile:144) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:497) at net.minecraft.launchwrapper.Launch.launch(Launch.java:135) at net.minecraft.launchwrapper.Launch.main(Launch.java:28) I was searching which packet is sent to player when hit by entity but I couldn't find anything so if you know which that'll help too. Edit: Happens everytime NPC hits another entity Edit 2: I guess the packet is something like play out animation but it's too late - gonna try it tomorrow.