Pitiless Plunderer + Wriggling Grub + Chthonian Nightmare + Yahenni, Undying Partisan

Pitiless Plunderer

Wriggling Grub

Chthonian Nightmare

Yahenni, Undying Partisan

How it works

1. Cast Chthonian Nightmare by paying 1.
2. When Chthonian Nightmare enters the battlefield, it triggers, causing you to get EEE.
3. Activate Chthonian Nightmare by paying EEE, sacrificing another creature and returning Chthonian Nightmare from the battlefield to your hand.
4. When the creature dies, Pitiless Plunderer triggers, creating a Treasure token.
5. Resolve the Chthonian Nightmare ability, returning Wriggling Grub from your graveyard to the battlefield.
6. Activate Yahenni by sacrificing Wriggling Grub.
7. When Wriggling Grub dies, it and Pitiless Plunderer trigger.
8. Resolve the Wriggling Grub trigger, creating two 1/1 Worm creature tokens.
9. Resolve the Pitiless Plunderer trigger, creating a Treasure token.
10. Resolve the Yahenni ability.
11. Activate the Treasures by tapping and sacrificing them, adding 1.
12. Repeat.