Silverblade Paladin

Double strike is one of the most punishing keywords to hand out for free, which is why most creatures that carry it pay a steep price in mana or restriction. The trick here is that the keyword lands twice: pair this with another attacker the moment either one shows up, and both bodies swing for double. A 2/2 that gives itself double strike already trades up; a 2/2 that turns a 4/4 alongside it into an eight-damage hit is doing aggression math no other three-drop in white quite matches. Soulbond is the lever that makes the rate honest. The pairing is fragile (it dissolves the instant you stop controlling either creature, and a removal spell on the Paladin strips the partner's double strike just as cleanly), so the payoff is gated behind keeping two threats on the board at once, exactly the position an aggressive deck wants to be in anyway and exactly the position a good blocker or sweeper denies. It rewards going wide, then converts that board presence into reach a turn faster than a fair deck expects. The structural cleverness is in pointing the double strike outward: the best target is rarely the Paladin itself but the biggest unpaired thing you already control, which makes every other creature in the deck a potential delivery vehicle for the most lopsided combat keyword in the game.