Sentinel's Mark

The whole design lives in the gap between two casting windows. Cast on the opponent's turn, at flash speed, it is a defensive Aura: a vigilant blocker that survives combat better than its numbers suggest. Cast while you hold the initiative and the addendum fires, handing the creature lifelink until end of turn and converting the same +1/+2 into a life-swing bolted to your alpha strike. The keyword is the mechanic that pays you for the tempo you give up: flash normally means holding priority and reacting, but this rewards you for committing proactively instead, inverting the usual calculus where the reactive line is the stronger one. The result is an Aura that reads as a combat trick when you need it to be one and a value play when you are the one dictating combat, without ever changing a word of what it does to the body. Auras have always carried the two-for-one risk that makes players wary of them; this softens that risk on the buyer's terms by letting you deploy at the moment of least exposure, either after blocks are declared or when you set the terms of the attack. It is a small card doing a precise thing: making the choice of when to cast matter as much as what it does.