Phyrexian Devourer

A combo finisher disguised as a self-destruct mechanism. The body starts as a 1/1, and every activation exiles the top card of your library to feed it: the more expensive the exiled card, the larger the swing in counters, and the closer it creeps to the threshold that sacrifices it. That tension between growth and self-destruction is the entire design. Left alone, it is a liability that eats itself the moment its power reaches 7. The trick the card invites is to redirect that power before the sacrifice trigger resolves, which is why it has spent its life paired with damage-redirection and power-dumping outlets that turn an arbitrarily large creature into an arbitrarily large burst of damage or life. The activated ability has no mana cost, so the only real limit on how big the construct gets in a single window is how many cards you are willing to exile and how fast you can offload the result. The sacrifice is a triggered ability, not an automatic check: when power hits 7 or more, the trigger goes on the stack, and the gap between that trigger and its resolution is the window the whole engine lives inside. It is a deck-builder's puzzle expressed as a single creature: the engine is on the card, but the payoff has to come from somewhere else. That dependency is what kept it a fringe curiosity rather than a staple, and also what made it beloved by the players who solved it.