Yarus, Roar of the Old Gods + Karlov Watchdog + Viscera Seer + Switcheroo

Prerequisites

• An opponent controls a creature.
• You control a face-down creature whose front face is a permanent card.
• You have enough mana to cast Switcheroo.

Steps

1. 1Cast Switcheroo by paying its mana cost, giving control of Karlov Watchdog to an opponent.
2. 2During the opponent's turn, activate Viscera Seer by sacrificing a face-down creature you control.
3. 3When 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. 4Resolve the Viscera Seer ability.
5. 5Repeat from step 2.

Effects

• Infinite creature ETB
• Infinite creature LTB
• Infinite creature sacrifice triggers
• Infinite death triggers
• Infinite scry 1