Stalwart Successor + Thermopod + Persistent Constrictor

Stalwart Successor

Thermopod

Persistent Constrictor

How it works

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

This loop relies on an elegant neutralization of persist drawbacks: when Persistent Constrictor dies, its own persist ability brings it back with a -1/-1 counter, but the presence of Stalwart Successor immediately counters that downside by triggering to place a +1/+1 counter on it instead. Since state-based actions cause +1/+1 and -1/+1 counters to annihilate each other, Persistent Constrictor is left clean and ready to feed into Thermopod's sacrifice outlet. You can repeat this sacrifice-and-return cycle indefinitely, generating an endless stream of red mana and death triggers while using Thermopod to fuel the engine.