Fleshtaker

The word "creature" in the trigger is the whole constraint: only sacrificing bodies pays out, so the Treasures, Clues, and Food that keep so many Orzhov sacrifice shells humming contribute nothing to this engine. It wants flesh specifically, and in exchange each creature you feed to your own effects returns a point of life and a scry, smoothing draws while the loop turns. What lifts it above the rack of two-drop enablers whose whole plan is a slow value drip is the activated pump, and the way that pump routes back through the same trigger. Its cost is one mana plus sacrificing another creature, and that sacrifice is itself a sacrifice you performed: the pump does not compete with the life gain and scry, it feeds them. Spend the mana and the fodder, and you get all three at once: +2/+2 on the clock, a life gained, and a dig for gas. The mana gate is what keeps this honest, since it means the outlet is not free and every activation costs a card in play and a floating one. On an empty board the abilities have nothing to chew on and the body sits idle, waiting for its supply line. Stocked, it converts dying creatures into sustain, selection, and a growing threat on the same decision, one activation at a time.