Stalwart Successor + Thermopod + Lingering Tormentor

Stalwart Successor

Thermopod

Lingering Tormentor

How it works

1. Activate Thermopod by sacrificing Lingering Tormentor
2. When Lingering Tormentor dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
3. When Lingering Tormentor enters, Stalwart Successor triggers, putting a +1/+1 counter on Lingering Tormentor
4. Repeat.

This loop sets up an infinite engine using Lingering Tormentor as the sacrificial fuel for Thermopod, generating an endless stream of red mana and death triggers. Every time Lingering Tormentor dies, its persist ability brings it right back to the battlefield with a -1/-1 counter, which normally spells doom for its recursion. However, Stalwart Successor swoops in with its triggered ability to offset that drawback, placing a +1/+1 counter on the Tormentor the first time counters are placed on it each turn. Because +1/+1 and -1/+1 (or -1/-1) counters annihilate each other state-based style, the Tormentor enters clean and ready to be sacrificed to Thermopod all over again.