This wither expansion makes the fight a little more interesting. If you spawn him, he has a few abilities.
1. Keeps you and ALL other entities towards him.
3. This is not a bug. He can actually trap you under the ground if in a certain location. This can lead to certain death!
4. HE IS INVINCIBLE TO ARROWS!!!! HAHAHAHAHA!!!! (Seriously. I suggest using a different range weapon that he couldn't be immune to. Better yet, use another command with a mega kewl weapon!)
5. Lag. Lots and LOTS of lag!