Yarus, Roar of the Old Gods, Karlov Watchdog, Blim, Comedic Genius, and Yahenni, Undying Partisan

Prerequisites

• Yarus, Roar of the Old Gods on the battlefield
• Karlov Watchdog on the battlefield
• Blim, Comedic Genius on the battlefield
• Yahenni, Undying Partisan on the battlefield
• Blim does not have summoning sickness and cannot be blocked by an opponent
• You control a face-down creature whose front face is a permanent card

Steps

1. Deal combat damage to an opponent using Blim
2. Blim triggers, giving control of Karlov Watchdog to an opponent
3. During the opponent's turn, activate Yahenni 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 Yahenni ability
6. Repeat from step 2

Results

• Infinite LTB
• Infinite ETB
• Infinite sacrifice triggers
• Infinite death triggers