Blightbeetle, Carrion Feeder, and Harmless Offering

Prerequisites

• Blightbeetle on the battlefield
• Carrion Feeder on the battlefield
• Harmless Offering in hand
• available

Steps

1. Donate Blightbeetle to an opponent Activate Carrion Feeder 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 Carrion Feeder ability
4. Repeat from step 2

Results

• Infinite LTB
• Infinite ETB
• Infinite sacrifice triggers
• Infinite death triggers
• Infinite +1/+1 counters on Carrion Feeder