To kill him.

I suggest spectre armor with mana flower,tons of mana potions,rage potion,wrath potion,magic power potion, bowl of soup,sorcerer emblem spooky wings, mana weapon of choice preferably homing. Flatten some land to run across,also I suggest frosts park boots. Make lots of asphalt blocks put them in a extremely long line you will also need gravitation potion.

Once  ready, fish with truffle worm and summon him.flip gravity often as  the movement falling is faster than his movement speed.kill him till he gives bubble gun as the bubble gun can do serious damage with a good setup it can do real damage when setup right