Phyrexian Colossus

The life payment is the whole design. An 8/8 for seven that comes down ready to swing would be a beating, but the body never untaps on its own, and the intended way to free it is to bleed yourself for eight life every turn you want it attacking. That is a punishing toll for a creature whose evasion clause means the opponent only has to commit three bodies to wall it, and the math gets worse the longer the game runs. Early designs of this sort sold the giant golem as a curiosity: a beater that asked you to mortgage your life total to stay on the offensive, with the price meant to be the brake on its size. The untap ability carries no tap requirement and no timing restriction beyond having the life to spend, but the cost itself does the gating. Eight life is eight life, paid out of a fixed total, and it caps how many times the colossus can come back in a game far more reliably than any blocker does. The rate looks abusable and is not, at least not by its printed text: nothing stops an outside untap effect from sidestepping the toll, which is precisely where any serious attempt to break the card has always pointed. Left to its own cost, the recurring life payment compounds against you, turning a beater into a clock on yourself as much as on the opponent.