Yarus, Roar of the Old Gods, Karlov Watchdog, Blasting Station, and Harmless Offering

Prerequisites

• Yarus, Roar of the Old Gods on the battlefield
• Karlov Watchdog on the battlefield
• Blasting Station on the battlefield
• Harmless Offering in hand
• You control a face-down creature whose front face is a permanent card
• You have enough mana to cast Harmless Offering

Steps

1. Cast Harmless Offering by paying its mana cost, giving control of Karlov Watchdog to an opponent
2. During the opponent's turn, activate Blasting Station by tapping it and sacrificing a face-down creature you control
3. 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
4. When the creature enters the battlefield, Blasting Station triggers, untapping Blasting Station
5. Resolve the Blasting Station ability from step 2
6. Repeat from step 2

Results

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