Yarus, Roar of the Old Gods + Karlov Watchdog + Phyrexian Altar + Coveted Falcon

Yarus, Roar of the Old Gods

Karlov Watchdog

Phyrexian Altar

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 Phyrexian Altar 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. Repeat from step 3.

This intricate loop transforms Coveted Falcon into a gift-giving engine that turns your board state into an endless resource: by paying its disguise cost to turn it face up, you hand an opponent control of Karlov Watchdog, which cleverly leverages its static ability to prevent permanents from being turned face up during your turn. This ensures that when you sacrifice creatures to Phyrexian Altar to generate infinite colored mana and death triggers, Yarus, Roar of the Old Gods continuously triggers to return those fallen creatures to the battlefield face down. Because Karlov Watchdog blocks them from flipping back up, they remain safely face down in the graveyard-to-battlefield cycle, ready to be sacrificed over and over again.