Yarus, Roar of the Old Gods + Karlov Watchdog + Bloodflow Connoisseur + Coveted Falcon

Yarus, Roar of the Old Gods

Karlov Watchdog

Bloodflow Connoisseur

Coveted Falcon

How it works

1. Activate Coveted Falcon by paying 1, turning it face up.
2. Coveted Falcon triggers, causing an opponent to gain control of Karlov Watchdog and causing you to draw a card.
3. During the opponent's turn, activate Bloodflow Connoisseur by sacrificing a face-down creature you control.
4. 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.
5. Resolve the Bloodflow Connoisseur ability.
6. Repeat from step 3.

This ingenious engine relies on a clever piece of rules interaction protected by Karlov Watchdog, whose static ability prevents permanents your opponents control from being turned face up during your turn—meaning when you hand it to an opponent with Coveted Falcon, you ensure it stays safely face down even as it triggers shenanigans. Meanwhile, Yarus, Roar of the Old Gods watches over your graveyard, turning any fallen face-down card straight back onto the battlefield whenever it dies, while Bloodflow Connoisseur cheerfully sacrifices those creatures to grow larger and feed the loop infinitely.