Requires

Nim Deathmantle must be on the battlefield. Ashnod's Altar must be on the battlefield. Ashaya, Soul of the Wild must be on the battlefield. Sporemound must be on the battlefield. Mana needed:

Steps

1. Activate Ashnod's Altar by sacrificing Ashaya, adding .
2. When Ashaya dies, Nim Deathmantle triggers, causing you to pay to return Ashaya from your graveyard to the battlefield, and attaching Nim Deathmantle to it.
3. When Ashaya enters the battlefield, Sporemound triggers, creating a 1/1 Saproling creature token.
4. Activate Ashnod's Altar by sacrificing the creature token, adding .
5. Repeat.
6. If you control a nontoken creature that has haste, you may instead sacrifice it, and then tap it each iteration to get infinite green mana and colorless mana.

Results