Double Cleave

Most combat tricks of this era bundled their keyword with a stat bump or a protection clause; this one does the opposite, paying its whole budget for a single ability and trusting the attacker to already be worth doubling. That trust is what makes the card a finisher rather than a tempo play. Double strike multiplies whatever the creature is already getting through: a trampler punches twice the surplus past a blocker, an unblocked attacker simply halves the opponent's remaining turns, and a creature carrying a connect trigger or lifelink doubles the payload that the trigger or the gained life rides on. It does nothing for a creature a chump blocker can stop without trample, the same as any pump would, so the math the card rewards is reach and evasion, not raw size. The window is the part worth respecting: held at instant speed through the declare-attackers step, it lets you commit nothing until blocks reveal whether the second hit is lethal, then convert a marginal swing into a kill after the opponent has already made their decisions. Costing one generic and one red-or-white pip, it runs the same whether a deck leans toward burn-and-haste or toward go-wide white aggression, and it slots into any shell touching either color without demanding a fixed source. As combat math it answers one question (is the extra strike enough to end this?) and asks two mana to find out.