Maraxus of Keld

A power-and-toughness gauge wired directly into the untapped state of your board, which is a stranger design knob than it sounds. Most "count your stuff" creatures (Tarmogoyf reads the graveyard, the various lords read a tribe) sum a static quality. This one sums a transient one: the size swings between your turn and your opponent's, between pre-combat and post-combat, between tapping for mana and floating that mana untapped. The number that matters is the number at the instant the game checks it, so the body is enormous when you attack into an open board and limp when you have just emptied your hands tapping out. The design lives in that volatility. It punishes you for using your resources the same turn you want Maraxus to be a threat, and it rewards a board built wide and left standing. The legendary frame and the steep cost mark it as an early attempt at a payoff that depends on the texture of your permanents rather than their count alone, before the design vocabulary for that idea had settled. It asks a question the rest of its era rarely posed: not how much do you control, but how much of it have you not yet spent.