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.

{T}: Add one mana of any color that a land an opponent controls could produce.

Flying Whenever this creature deals combat damage to a player, look at the top three cards of that player's library, exile one of them face down, then put the rest into their graveyard. You may cast that card for as long as it remains exiled, and mana of any type can be spent to cast that spell.

Look at the top two cards of target opponent's library. Exile one of them face down and put the other on the bottom of that library. You may play the exiled card for as long as it remains exiled, and you may spend mana as though it were mana of any color to cast that spell. Flashback {1}{U}{B}

Exile all opponents' graveyards. You may cast spells from among those cards this turn, and mana of any type can be spent to cast them. At the beginning of the next end step, if any of those cards remain exiled, return them to their owners' graveyards. Exile Mnemonic Betrayal.