Mecha Mobzilla (mob name Kiryu) is a robotic form of Mobzilla crafted with tons of resources and used as the primary way to kill Mobzilla himself. Mecha Mobzilla will never hurt or kill a player, even if provoked, but he will knock back aggressive ones.
Right click on the ground with 10 "Summon Kiryus" to spawn him in. He is automatically tamed and bound to the player who spawned him. While Mecha Mobzilla will attack hostile mobs, his best and most obvious use is to fight Mobzilla.
Mecha Mobzilla only has two abilities. His first is the standard hit that does a little less than Mobzilla, and one finishing move that gives Mobzilla a Poison 50 affect that, if used correctly, can kill Mobzilla.