Shapeshifter

A dial, not a fixed body. The design idea is that power and toughness always sum to seven, and you reset the split each upkeep: a 0/7 wall on one turn, a 4/3 the next, a 6/1 attacker the turn after. You cannot dial all the way to 7 power, because that leaves 0 toughness, and a creature with 0 toughness dies immediately to a state-based action before it can do anything. The offensive ceiling is 6/1. The math is elegant in a way early Magic rarely bothered with, and the choice sits on the beginning of your upkeep, before your main phase and combat: you pick the new split and then attack with it that same turn, so the slider is genuinely live rather than telegraphed a turn in advance. The real constraint is that you commit to the number during the beginning phase, well ahead of declare attackers and declare blockers, so you lock in a configuration before the turn shows its hand. That is not a combat trick; it is a standing posture you choose once per turn and then live with. What the card is really doing is asking how to make a body interesting through its stat line alone, without an evasion keyword or an enters-the-battlefield payoff. The variable size is the whole texture: a creature whose shape is a decision you keep making, on an artifact frame any deck can run.