Shirei, Shizo's Caretaker

The recursion bands tightly: only creatures with power 1 or less, and only at the next end step rather than the moment they die. That restriction reorients the whole build. You cannot loop fatties or even mid-sized threats through this; you assemble a deck where every body is a small one and the death itself is the resource worth banking. The delayed return does real work. A creature dies now and comes back later, which means a sacrifice outlet plus a one-power body becomes a repeatable engine: each cycle is a fresh dies trigger, a fresh enters-the-battlefield trigger, and a fresh body to feed back in. The whole structure hinges on Shirei surviving (the ability rechecks for it on the battlefield each end step), so a deck running this engine pays a tax in protection on top of everything else. It stands as one of black's earliest swings at turning the recursion of small, expendable creatures into a deck-defining strategy rather than incidental graveyard value: not a Reveillark-style toolbox in white, not the brute-force reanimation of a single haymaker, but a swarm that keeps returning precisely because no individual piece was ever worth a removal spell. Disposability is the engine. The creatures Shirei rewards are the ones opponents shrug off, and that indifference is exactly what lets them recur.