Fertilid + Nissa, Resurgent Animist + Felidar Retreat + Horizon Explorer

Fertilid

Nissa, Resurgent Animist

Felidar Retreat

Horizon Explorer

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 Horizon Explorer.
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.