Funny enough, one of my favorite Standard decks I've ever played was a Delirium deck
Getting to 20 cards in Commander isn't hard at all, in a strategy designed to enable that
The Legend of Kuruk / Avatar Kuruk The Legend of Kuruk lets you Preordain twice before it becomes a finisher in Avatar Kuruk, which acts like a Young Pyromancer
(If a permanent with a stun counter would become untapped, remove one from it instead.) Creature - Homunculus Splash Lasher Offspring (You may pay an additional as you cast this spell
Since all the combos require my commander to instantly win, a quick n' easy way to do this would be just to swap Niv-Mizzet, Parun out with a noncombo commander and call it a day: Niv-Mizzet, Dracogenius is a straightforward swap if you still want to keep The Firemind in your command zone, or you can switch to another Spellslinger commander like Kaza, Roil Chaser
That's just scratching the surface, and it's worth mentioning that, even if it turns into another creature for the turn, Scion still doles out commander damage
