Ha, believe it or not, Trillion is actually pretty underpowered.
Sure, he can spam out a trillion blades at you, but unless you fed him absolutely horribly all game he's going to get even halfway there, the blades deal subpar damage (even when you got so many of them) and aren't very hard to dodge.
Yeah, he's not powerful at all, since you have to build up that blade stock. Normally you'll be lucky to get a few thousand, and that's just a short burst of bullet hell. In most games you basically treat him as a one-off bomb attack that you waited all game to build up.
But where he shines is against minion generators. Guys like Mechromancer, who has tons of troops that both reraise and hit Heroic tier quickly? With his hero-kill ammo bonus, Trillion actually makes more ammo than he loses, ramping up and spamming blades over the whole map indefinitely! That ends summoner teams
fast.
(He's neat against Red Baron, too. I expect that to be patched within a couple of days, since right now an evasion build can actually
solo the dude by dodging his beam spam and feeding off the horde of heroic minions. The devs have made it plenty clear their pet superboss was never meant to be soloable.)
But it's pretty clear he was always intended as a silver bullet for Mechromancer, and oddly enough Truffle with his fungus minions. Looks like they dropped the ball with Truffle, though.