First get him down 10,000 hp then stun him he should revive 2,000,000 hp, so use subversion and it will do 2,000,000-3,000,000 damage, and killing him 1 hit.
Also for Doctor Kilma I think thats what hes called you have to subversion him/retrograde for multiple times its very precise and difficult or at least I think thats what you have to do
