Fertilid + Nissa, Resurgent Animist + Felidar Retreat + Spelunking

Fertilid

Nissa, Resurgent Animist

Felidar Retreat

Spelunking

How it works

1. Activate Fertilid by paying 1 and removing a +1/+1 counter from it, causing you to search your library for a basic land card and put it on the battlefield untapped due to Spelunking.
2. When the basic land enters, Nissa and Felidar Retreat trigger.
3. Resolve the Nissa trigger, adding .
4. Resolve the Felidar Retreat trigger, putting a +1/+1 counter on Fertilid.
5. Activate the basic land by tapping it, adding 1.
6. Repeat.

This clever loop turns Fertilid into an endless engine for land progression by feeding its own activation cost right back to it. Thanks to Spelunking ensuring that every searched land enters the battlefield untapped, you can immediately tap that new land to help pay for Fertilid's ability while simultaneously fueling Nissa, Resurgent Animist and Felidar Retreat. Every single landfall trigger from Felidar Retreat places a fresh +1/+1 counter back onto Fertilid to replace the one you just spent, keeping the cycle going indefinitely. Meanwhile, Nissa, Resurgent Animist cascades through your mana production and helps filter through your deck, turning a humble elemental into a catastrophic avalanche of basic lands.