Wow. What to say? There has never been a mob this destructive, this powerful, this ridiculously insane... He's obviously had a very bad day and is venting some serious frustration. Are you sure you really want to mess with him? Try flying around and following him for a while in creative mode. It is best to thoroughly know your enemy before battle. Maybe you'll change your mind and just leave him alone. Probably a good idea anyway… Find him in the Village Dimension!
Mobzilla has two hit boxes, one around his feet, the other around his head.
Make sure to get the scales after you kill him! Awesome Mobzilla Armor!!!
Summons lightening strikes
Tail swing to destroy everything
Jumps cause earthquakes and destruction
How to Spawn
If you're trying to find an egg, you will need 9 Ancient Dried Mobzilla Egg Parts in order to make one egg. Good luck! Check the Mining Dimension for a ton of OreSpawn!
How to Kill
Is that a serious question? You'll need the strongest armor, the Big Bertha Sword, a few Enchanted Golden Apples, maybe a Cephadrome or two or three, and some patience and persistence. Other than that, make sure you are fireproof. Being blast-resistant helps too. A few speed potions could be handy, as he moves rather quickly. And lastly, don't even bother trying to sneak up behind him. That tail is deadly!
BigBertha and a few hoverboards seem to work well too. Bring along a Skate Bow and a couple stacks of Irukandji arrows to shoot him with while you're waiting to drop back down from when he whacks you up sky-high!
Just for Fun
Spawn him next to a village! Watch him flatten it!
Found: Rainbow Ant Village World
Drops: Ridiculous amounts of stuff!!! Lots of Mobzilla Scales!