Grovetender Druids + Conspiracy + Ashnod's Altar

Grovetender Druids

Conspiracy

Ashnod's Altar

How it works

1. Cast Grovetender Druids by paying 2.
2. When Grovetender Druids enters the battlefield, it triggers, causing you to pay 1 to create a 1/1 Plant creature token.
3. When the Plant enters the battlefield as an Ally due to Conspiracy, Grovetender Druids triggers.
4. Holding priority, activate Ashnod's Altar by sacrificing the Plant, adding CC.
5. Resolve the Grovetender Druids trigger, causing you to pay 1 to create a 1/1 Plant creature token.
6. Repeat from step 3.
7. Once you have infinite mana, you may forego sacrificing the Plants.

This loop turns a simple rally trigger into a self-sustaining engine by rewriting the rules of the battlefield with Conspiracy, which ensures every creature you own—including the tokens you make—counts as an Ally. Because of this shared creature type, every time a new token appears, Grovetender Druids triggers anew to offer another Plant for just one mana. You can then feed that freshly spawned Plant directly into Ashnod's Altar to generate two colorless mana, leaving you with a surplus to easily pay the Druids' rally cost and still come out ahead.