Since I got lazy and didn't want edit the video the instructions are here, first upgrade your bank to 4 then spawn in dual speed battlers until you kill the firebrand guys, then wait for spartan, sailor and bucket to get to your base when they're close use slammer while saving up for bank again and spam soccer and galoa to ensure constant knockback on enemies. And once your just bank level is really high and you got alot of npcs, just spam whatever and eventually you will kill the boss.