As long as your devotion to white and black is less than seven, Athreos isn't a creature.
At the beginning of your end step, put a coin counter on another target creature.
Whenever a creature with a coin counter on it dies or is put into exile, return that card to the battlefield under your control.
Drop coin counters on the best creatures on the board, then kill or exile them so they return under your control. You build a high-devotion BW board, steal opponents' key creatures, and grind value while abusing death/exile triggers. Win by accruing overwhelming card and board advantage, or by chaining a sacrifice loop into a kill.
Indestructible commander that's nearly impossible to remove permanently and re-enters easily
Repeatable, color-flexible theft of any creature in the format via coin counters
Excellent synergy with sac outlets and removal you already run for value
Rewards a heavy permanent base, naturally hitting devotion to turn Athreos on
The steal is slow—one coin counter per end step and you need to kill the creature to claim it
Vulnerable to graveyard hate and exile-that-doesn't-trigger-return effects on its own pieces
Relies on Athreos sticking; bounce, tuck, or counterspells slow the engine
Can be a glass cannon if the board is wiped and your devotion drops below seven
Recurs Athreos-fueled permanents and cheap sac fodder for relentless grind.
Add efficient free or cheap sac outlets (Ashnod's Altar, Viscera Seer, Carrion Feeder) so coin counters convert to permanent theft immediately rather than waiting on natural death. Layer in aristocrats payoffs (Blood Artist, Zulaport Cutthroat, Bastion of Remembrance) and recursion (Sun Titan, Karmic Guide, Reanimate) to turn every death into value. Improve the mana with fast rocks and dual lands, and consider a compact combo like Mikaeus or sacrifice loops to close games before the slow engine gets answered.
Legendary Enchantment Creature — God
