Evernight Shade

The Shade has been black's mana-sink creature since the earliest days of the game: a 1/1 body with a repeatable pump that converts excess black mana into combat damage. Frozen Shade set the template, where one black mana buys a point of size for the turn. The recurring weakness of the type is the trade: tap out to attack, eat a removal spell, and the body dies before it has earned back what you fed it. Undying answers that specific failure, not by preserving the invested mana (the pump is an until-end-of-turn boost on the original object, and it does not survive the death) but by preserving the creature itself. Kill the Shade during your alpha strike or in response to a pump, and it returns as a 2/2 carrying a +1/+1 counter, ready to soak mana all over again next turn. The two abilities never collide, because the pump grants temporary bonuses and never places counters; the body stays counterless through your attack, so undying always fires the first time it dies. The catch is built into that same clause: undying only returns a creature that died with no +1/+1 counters, and the returned copy already carries one. The first death is the free one, the second is permanent, so the recurring Shade is a slow attrition threat rather than an engine. A modest creature doing a familiar job, but the pairing is tidy: the thing that usually punishes you for committing to a Shade is exactly the thing undying shrugs off once.