Whenever you cast a spell you don't own, create a 3/3 black Demon creature token.

+1: Draw a card. For each opponent, exile up to one target instant or sorcery card from that player's graveyard and put a page counter on it.

−3: You may cast a spell from among cards in exile with page counters on them without paying its mana cost.

Tasha, the Witch Queen can be your commander.