Enshrouding Mist

The base mode is a fog stapled to a single body: one white mana prevents all damage that would hit that creature this turn, while the +1/+1 lets it trade up or shrug off a burn spell sized to kill it. The prevention clause is narrower than it reads, and the narrowness is the point. It blanks combat damage and damage-based removal but does nothing against destroy, exile, or bounce, so this is insurance against one specific kind of threat, not catch-all protection. The renown rider is where the design earns its second purpose. Renown only sticks once a creature has already connected with a player, so this rewards you most on a creature that was renowned on a previous turn: send it in, win the fight or eat the removal it was aimed at, then untap it so the attacker that just carried the offense is back up to block the crack-back. That converts a body committed to the attack into one that also holds the line, all at instant speed and for a single mana. The card is built to pay out exactly when you are pressing the aggressive plan with a threat that has already earned its renown, folding a generic combat instant onto the attack-and-grow keyword it was made to support. As a standalone defensive trick it is workable; as a reward for the tempo renown asks you to spend, it turns your best attacker into an attacker that defends too.