Altar of Dementia

A free sacrifice outlet that converts power into mill, and free is the operative word: no mana, no tap, no once-per-turn limit on the activation. That absence is what makes it dangerous. Most sacrifice outlets ask for something (mana, a tap, a cap) precisely because a costless one is an engine waiting to be abused, and this is the engine. Pair it with a way to make creatures (tokens, recursion, a creature that copies itself) and the loop turns sacrifice fodder directly into a deck-emptying alternate win condition, all at instant speed in a single pass. Because the mill targets any player, the same outlet that fuels your own graveyard can point at an opponent's library and end the game. The discipline lives entirely in what you feed it: the rate scales with the sacrificed creature's power, so a swarm of small bodies barely moves the needle while a single large creature, or an infinite supply of any creature, empties a library. Later sets learned to gate their free outlets more carefully precisely because of cards like this; its longevity as a mill payoff has less to do with the mill itself than with the freedom of the activation. The card asks nothing, so the only constraint on the loop is whatever you build around it.