Iron Will

Pure toughness pumps have always been the weakest combat tricks in white: they save a creature in combat but do nothing on offense, and a hand full of dead defensive spells is how games slip away. Urza's Legacy answered that problem across a cycle of one-mana effects by stapling cycling to them, turning the floor of a narrow trick from "a dead card" into "two generic mana for a fresh draw." That single addition rewrites the deckbuilding math. A defensive spell that does nothing against half of opponents normally would not earn a slot, but one that converts into a card whenever it is irrelevant carries no opportunity cost. The +0/+4 itself is built to blank burn and survive trades rather than win them: it pushes a creature out of damage-based removal range and lets a smaller blocker eat a larger attacker without dying. The design lives in the menu it hands you each turn: protect the creature now, or pitch the card later for something live. It demonstrates cycling working as a tension-resolution mechanic, smoothing the variance that makes situational tricks unplayable while preserving the trick for the moment the window actually opens.