Sister Repentia
A 5/1 body is a threat with a countdown built in: it dies to any blocker, any ping, any incidental sweep, and the design leans all the way into that fragility rather than papering over it. The Martyrdom trigger turns the inevitable death into a payoff (two life and two cards), which converts a creature you would normally hate to lose into one you are happy to throw into unfavorable combat. That inversion is the whole trick. Power five on one toughness makes it an eager attacker whose damage rarely matters as much as the trade it invites, and every sacrifice outlet in the deck reads it as a draw-two on demand. Miracle stacks a second gamble on top: when it comes off the top as your first draw, the black-white cost lets you deploy it for a fraction of its face price, so the same card can arrive as a cheap aggressive body or as a full-value fling depending on how the turn breaks. The flavor of a Sisters of Battle penitent charging to her death is unusually well-matched to the mechanics here; the card wants to die, and dying is the point. What it represents in design terms is a martyr enabler dressed as a beater: a creature built to be spent, not protected, rewarding the player who treats their own board as fuel.

