Shane.
I hope you don't mind me doing this, but...
The Coolio boss fight. I figured it'd be better if the player battled
two of him first, having to defeat one of them in order to defeat the other.
The real Coolio is invulnerable, but his clone isn't. Once his clone is defeated, the real Coolio can be defeated.
I hope that's okay with you...
I kinda think it's an awesome idea. You don't get those sort of boss fights in
Cave Story mods often, right?