Vilis, Broker of Blood

Black's classic life-into-cards engines all came with a governor bolted on: Necropotence exiles what you'd draw and eats your turn, Greed rations one card per activation, Dark Confidant deals its damage before the card lands. This demon strips the meter out. Every point of life lost, from any source, in any amount, becomes a card, and the effect scales in a straight line with no ceiling. That is the tension the design has to answer, and it answers it by welding the payoff to a body that manufactures the losses itself: the activated ability spends both black mana and two life to shrink a creature, so every removal use is also a draw trigger. Aim it at your own board, kill something you couldn't otherwise touch, crack a fetch, take a swing in combat, and cards arrive in multiples rather than singletons. The finishing wrinkle is that damage counts as life loss, so a burn spell or an unblocked attacker that would ordinarily just chip your total refills your hand instead. The 8/8 flying frame and the triple-black cost are the counterweight: this is a payoff you have to reach and then protect, not a value creature you deploy on curve. Once it resolves and your life total becomes spendable, the cap on card advantage is essentially whatever life you have left.