Perhaps add Gheden or some other form of nonlethal immunity. Could also add Troll-Blooded so they'd have to find some way to bypass the regenerations to damage it, or an immunity-bypassing SoD of some kind. Or Dark for HiPS? It already has Camouflage; could be hilarious for a Colossal thing to hide in front of you. Its offense could use a bit of a punch; so much resource into defenses that it doesn't do much vs. FoM targets. Hmm, some At-Will Illusions feel vindicated for fey things. Can't think of an easy source right now though.