The Master, Formed Anew, and Thermopod

Prerequisites

• The Master, Formed Anew on the battlefield
• Thermopod on the battlefield

Steps

1. Activate Thermopod's second ability by sacrificing The Master, adding
2. When The Master dies, if it was a copy of the undying creature, its undying ability triggers, returning it from your graveyard to the battlefield as a copy of the persist creature with a +1/+1 counter on it
3. Otherwise, if The Master was a copy of the persist creature, its persist ability triggers, returning it from your graveyard to the battlefield as a copy of the undying creature with a -1/-1 counter on it
4. Repeat

Results

• Infinite creature LTB
• Infinite creature ETB
• Infinite creature sacrifice triggers
• Infinite death triggers
• Infinite red mana