DreadKyller

I am attempting to create a mod, which so far is working well. In this mod I've created a class that extends Entity witch, and I am using events to intercept when a potion is being thrown by this new witch. I tested it out in single player, in Minecraft, the entity for a potion is ThrownPotion, while in the code ThrownPotion doesn't exist and is instead EntityPotion (from what I can tell). In game with command blocks I can execute this command and it works perfectly: /summon ThrownPotion ~ ~2 ~ {Potion:{Count:1,id:373,Damage:16428,tag:{CustomPotionEffects:[{Id:20,Amplifier:0,Duration:200}]}}} It was my belief that the same NBT structure should work for EntityPotion as well. Since I'm adding a wither potion effect I can't just set the damage, as id=20 is above the 15 allowed in the first 4 bits of the id, which define the potion effect, so I have to use custom potion effects. The problem is the nbt format isn't working. The following is the code: @SubscribeEvent public void onEntitySpawn(EntityJoinWorldEvent event) { Entity e = event.entity; if(e instanceof EntityPotion) { EntityPotion ep = (EntityPotion)e; if(ep.getThrower() instanceof ChargedWitch) { if(ep.getPotionDamage() != 32660) return;// Only alter the poison potion thrown by the witch ep.setPotionDamage(16461); // If this line is here, potion becomes instant damage, is commented potion is still poison // (proving nbt didn't work) NBTTagCompound nbt = ep.getEntityData(); NBTTagCompound potion = nbt.getCompoundTag("Potion"); NBTTagCompound tag = new NBTTagCompound(); potion.setShort("id", (short) 373); potion.setShort("Damage", (short) 16461); potion.setByte("Count", (byte) 1); tag.setTag("CustomPotionEffects", makePotion()); potion.setTag("tag", tag); nbt.setTag("Potion", potion); } } } public NBTTagList makePotion() { NBTTagList list = new NBTTagList(); NBTTagCompound potionType = new NBTTagCompound(); potionType.setByte("Id", (byte) Potion.wither.getId()); potionType.setByte("Amplifier", (byte) 0); potionType.setInteger("Duration", 200); potionType.setByte("Ambient", (byte) 0); //Not ambient list.appendTag(potionType); return list; } I'm unsure why this isn't working. I guess my main question is why is it ThrownPotion in game, but no sign of any "ThrownPotion" class in the project. If it's not possible I can easily make my own potion entity, I know enough to do so, I've just never experienced this issue before with inconsistent NBT structures. !EDIT: Changed topic title to fit the format most posts are using. !!EDIT: Thanks for the help, for anyone else looking to add custom effects to Potion Entities but don't know how: