Undying Evil

A sacrifice insurance policy you can hold up at instant speed. The trick is in where it lands the trigger: undying only returns a creature if it had no +1/+1 counters when it died, so granting it the turn the creature is about to be eaten leaves it pristine, then sends it back with a counter and the death triggers already collected. That makes this a one-mana way to double-dip on enters-the-battlefield and dies effects, to protect a key creature from targeted removal, or to turn a chump block into a body that comes back bigger. The window is the cleverest part: cast it in response to a kill spell on the stack, and the creature dies with undying live, returning before your opponent has spent another card. The cost of the keyword is built into its own text, since the very counter undying grants is what shuts it off on the next death; without an outside way to remove counters, each creature only loops once. It rewards a board built on small, expendable creatures with stacked death payoffs rather than a single fattie worth saving, which is exactly the aristocrats shape this kind of effect tends to live in.