Features include a boss bar that goes down when u hit a button at the right time 3 different attacks chosen at random (doors opening for gaurdians laser beams bones from the floor pushing u up into lava and dispensers spawning skeletons) an attack where he just laughs at you and a really bad rendition of sans
To be added:
Command blocks that say his lines when you do damage to him
A noteblock rendition of megalomania
by Candid_Emu_3951