Blightbeetle, Harmless Offering, and Bloodthrone Vampire

Prerequisites

• Blightbeetle on the battlefield
• Harmless Offering in hand
• Bloodthrone Vampire on the battlefield
• available

Steps

1. Use Harmless Offering to give Blightbeetle to an opponent Activate Bloodthrone Vampire 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 Bloodthrone Vampire ability
4. Repeat from step 2

Results

• Infinite creature ETB
• Infinite creature LTB
• Infinite creature sacrifice triggers
• Infinite death triggers
• Infinitely large creature until end of turn