Gwen Valen, Grand Witch

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

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.

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

Gwen Valen can be your commander.