Wow--legitimately did not expect to have the final boss completely functional this fast. I had spent so much time nervous over what I was gonna do for Kranion, and I basically whip out this fight in 3 days at most. His first phase still needs his placeholder sprites replaced, and I'm sure I'll need to do some rebalancing, but that's pretty much it.
Kranion's second form is Kranion Ultimate Edition, a really goofy named black hole with IMO a super cool looking face. You'll need to fight him with the jetpack. He'll float around the screen, and sometimes grow a ring of spikes around him and do one of two things; he'll either try to suck you into his spikes while shooting fireballs, or he'll bounce around the screen. Simple, but effective--just like the game itself really.