Fertilid + Lotus Cobra + Retreat to Kazandu + Horizon Explorer

Fertilid

Lotus Cobra

Retreat to Kazandu

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 Retreat to Kazandu trigger.
3. Resolve the Lotus Cobra trigger, adding .
4. Resolve the Retreat to Kazandu trigger, putting a +1/+1 counter on Fertilid.
5. Activate the basic land by tapping it, adding 1.
6. Repeat.