Furious Resistance

Combat tricks almost always reward the attacker; this one inverts the contract. The +3/+0 and first strike only land on a creature that is already blocking, which means the card sits dead in your hand until your opponent commits to combat and then punishes them for it. That restriction is the whole proposition: a defending player baits an attack into a blocker that looks like a clean trade, then ambushes the incoming creature, kills it with first strike before damage comes back, and walks away even on cards. It is a deterrent disguised as a single mana of upside, the rare trick that taxes the attack step rather than the block. The cost of that specialization is real: against an opponent who never attacks into open red mana, or who simply trades on their own terms, the spell does nothing, and it cannot be repurposed into a finisher or a racing tool the way a generic pump spell can. Red rarely gets handed defensive tools at all, which makes the design notable less for its rate than for its orientation; it asks the red player to hold up mana and play the patient half of a combat math problem, a posture the color is usually built to avoid.