Yarus, Roar of the Old Gods + Karlov Watchdog + Umbral Collar Zealot + Coveted Falcon

Yarus, Roar of the Old Gods

Karlov Watchdog

Umbral Collar Zealot

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 Umbral Collar Zealot 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 Umbral Collar Zealot ability.
6. Repeat from step 3.