Palantír of Orthanc

A Faustian bargain rendered as a card, and one that hands the choice to the wrong person on purpose. On each of your end steps it grows its own threat and then offers the opponent a devil's deal: let you draw a card now, or refuse and make you mill while they lose life scaled to what you dug up. That refusal clause is the whole engine's tension. The counter never stops climbing, so each turn the "safe" option (giving you a card) gets less safe by comparison, while the punishing option gets more punishing. The mill total and the life loss are lashed together through mana value, which means the artifact rewards a deck stuffed with expensive cards it wouldn't mind milling: the fatter the graveyard casualties, the harder the hit. Note who owns the decision. The opponent is the one squeezed, and a good pilot's job is to make both branches hurt, letting the drawn cards refill a hand while the declined ones drain a life total. It also quietly self-mills you when the influence counters get high, so the payoff and the cost live in the same number, and the artifact eventually threatens to run you out of library if left unchecked. This is a symmetrical-looking prison that isn't symmetrical at all: you set the terms, the opponent picks the poison, and both scale up the longer the palantír sits on the battlefield.