Skirsdag High Priest

The arithmetic here is brutal and that is the point. To make a 5/5 flier you tap this Cleric, tap two more untapped creatures, and you need a creature to have already died that turn: four bodies committed in service of one. That tax is what keeps a recurring Demon engine from being a runaway. The cleverness is that aristocrats decks satisfy the morbid clause incidentally; every chump block, every sacrifice for value, every token fed to an outlet flips the priest online. So the cost that looks prohibitive in a vacuum becomes nearly free in the decks that want the effect, because those decks are already manufacturing deaths as a byproduct of their normal operation. The tension it resolves is converting a wide, expendable board into a single resilient threat that flies over the ground stalls those decks tend to create. It rewards the player who has overcommitted to the battlefield rather than punishing them, turning the surplus of small creatures (the exact thing a sweeper preys on) into successive evasive 5/5s the moment something has bled out. Note how fragile the engine is on the front end: removal trades up against the priest before it ever produces a Demon, so the effect has to be protected and earned rather than deployed and forgotten.