Steadfast Unicorn

White commons have carried this shape for decades: a small body stapled to an activated team pump you hold until the swing decides a game. The vigilance rider is the detail that earns its keep. A one-shot buff that only tapped your attackers would leave you naked on the crack-back; folding vigilance into the same activation means the turn you grow your board is also the turn it can hold the line, so offense and defense collapse into a single choice. The your-turn-only clause blocks the instant-speed ambush that a true combat trick lives on: you can only pump on your own turn, which favors a deck already leaning into the attack over one banking on a surprise during the opponent's step. That makes it a repeatable finisher for a wide, low-curve white deck that wants its threats to keep coming online after the first wave. Filler by rarity and role, but the honest kind: a spare one-drop that doubles as an inevitability engine when the game grinds long.