Fertilid + Felidar Retreat + Lotus Cobra + Horizon Explorer

Fertilid

Felidar Retreat

Lotus Cobra

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, Lotus Cobra and Felidar Retreat trigger.
3. Resolve the Lotus Cobra 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.