Thermopod, and Yuna, Grand Summoner

Prerequisites

• Thermopod on the battlefield
• Yuna, Grand Summoner on the battlefield

Steps

1. Activate Thermopod by sacrificing the persist creature that has a +1/+1 counter on it, adding
2. When that creature dies, its persist ability and Yuna trigger
3. Resolve Yuna's ability, putting at least two +1/+1 counters onto the surviving persist creature due to the counter-increasing effect
4. If that creature had a -1/-1 counter on it, remove that and one of the +1/+1 counters from it as a state-based action
5. Resolve the persist ability from step 2, returning the persist creature from your graveyard to the battlefield with a -1/-1 counter
6. Repeat

Results

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