Ulasht, the Hate Seed + Agatha's Soul Cauldron + Wildwood Mentor + Thermopod

Ulasht, the Hate Seed

Agatha's Soul Cauldron

Wildwood Mentor

Thermopod

How it works

1. Activate Wildwood Mentor using Ulasht's ability by paying 1 and removing a +1/+1 counter from it, creating a 1/1 Saproling creature token.
2. When the Saproling enters the battlefield, Wildwood Mentor's first ability triggers, putting a +1/+1 counter on itself.
3. Activate Thermopod's second ability by sacrificing the Saproling, adding .
4. Repeat.

This ingenious engine is fueled by Agatha's Soul Cauldron granting Ulasht, the Hate Seed the sacrifice-for-mana ability of Thermopod, allowing Ulasht to directly utilize Thermopod's text while sitting safely on the battlefield. With that ability in hand, Ulasht pays to remove its own counters to create Saproling tokens, which in turn trigger Wildwood Mentor to rebuild Ulasht's counter supply whenever they enter. Finally, Thermopod steps in as the sacrifice outlet to recycle those very Saprolings into the red mana needed to keep the loop going endlessly.