Kraven, Proud Predator
Most creatures with variable power set it by counting something you build toward: creatures on the battlefield, cards in a graveyard, life paid. This one reads the ceiling instead of the count. Its power tracks the single most expensive permanent you control, which means the deckbuilding lever is not width but height: one fatty, one heavy artifact, one splashy planeswalker, and a three-mana Warrior swings for far more than its cost suggests. The four toughness anchors it against the removal that punishes glass-cannon bodies, and vigilance lets it hold the fort while it attacks, so the payoff is not contingent on going all-in on offense. The tension worth noticing is that the power source and the creature are decoupled: you are not paying to pump Kraven, you are being rewarded for playing expensive permanents you already wanted, then getting a beater as a rider. That inverts the usual green-red aggro question. Ramp decks normally want big spells for what those spells do; here the size of the biggest thing you resolve is itself an aggressive resource. It also sidesteps a weakness common to "power equals X" creatures, which is that they read as zero the moment the count empties: as long as anything meaningful is on the board, the highest mana value present tends to be respectable, so the floor is rarely embarrassing.
