Shadow the Hedgehog seems like a frontrunner, in terms of power at least, due to how chaos control effectively makes any spell that you cast with a Treasure or mana rock uncounterable
15 Magiccards per Draft Booster
Oak has something really important to tell you
Azorius and Jund: The Eighth Doctor & Jo Grant and Disa the Restless Dimir and Naya: Oskar, Rubbish Reclaimer and The Fugitive Doctor & Tegan Jovanka Rakdos and Bant: Anje Falkenrath and Ellie and Alan, Paleontologists Gruul and Esper: Borborygmos Enraged and Toluz, Clever Conductor Boros and Sultai: Osgir, the Reconstructor and The Mimeoplasm Simic and Mardu: Slogurk, the Overslime and Kroxa and Kunoros Some of these are pure graveyard, some of these rely more on other synergies that I think may distract too much from the target of our decks being built
Ishizu used "Exchange of the Spirit", causing both players to swap the contents of their Decks with their Graveyard, leaving Kaiba with very few cards
Proven track record