Yarus, Roar of the Old Gods + Karlov Watchdog + Viscera Seer + Iroh, Tea Master

Yarus, Roar of the Old Gods

Karlov Watchdog

Viscera Seer

Iroh, Tea Master

How it works

1. Donate Karlov Watchdog to an opponent.
2. During the opponent's turn, activate Viscera Seer by sacrificing a face-down creature you control.
3. When the creature dies, Yarus's second ability triggers, returning it from your graveyard to the battlefield face-down as a 2/2 creature, and then not turning it face-up due to Karlov Watchdog.
4. Resolve the Viscera Seer ability.
5. Repeat from step 2.

This cunning loop relies on a clever rules interaction involving Karlov Watchdog, which you donate to an opponent using Iroh, Tea Master's combat trigger so its static suppression ability blocks cards from turning face up *on your turn*. With that restriction in place, you sacrifice a face-down creature to Viscera Seer, which sends it to the graveyard and triggers Yarus, Roar of the Old Gods. Yarus dutifully attempts to return the permanent face down and turn it face up, but Karlov Watchdog prevents the face-up transition, leaving the creature safely face down on the battlefield ready to be sacrificed all over again.