Blightbeetle, Harmless Offering, and Yahenni, Undying Partisan

Prerequisites

• Blightbeetle on the battlefield
• Harmless Offering in hand
• Yahenni, Undying Partisan on the battlefield
• available

Steps

1. Donate Blightbeetle to an opponent Activate Yahenni by sacrificing the undying creature
2. When the undying creature dies, its undying ability triggers, returning itself from your graveyard to the battlefield without a +1/+1 counter on it due to Blightbeetle
3. Resolve the Yahenni ability
4. Repeat from step 2

Results

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