Fertilid + Tireless Provisioner + Bristly Bill, Spine Sower + Horizon Explorer

Fertilid

Tireless Provisioner

Bristly Bill, Spine Sower

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, Tireless Provisioner and Bristly Bill trigger.
3. Resolve the Tireless Provisioner trigger, creating a Treasure token.
4. Activate the Treasure by tapping and sacrificing it, adding .
5. Resolve the Bristly Bill trigger, putting a +1/+1 counter on Fertilid.
6. Activate the basic land by tapping it, adding 1.
7. Repeat.

This clever loop turns Fertilid into a self-sustaining land-tutoring engine by feeding its own counter-removal cost right back into itself. With Horizon Explorer ensuring your fetched lands enter untapped, every search drops a land to trigger Tireless Provisioner—whose resulting Treasure can be sacrificed for the green mana needed to keep going—while Bristly Bill, Spine Sower simultaneously replaces the +1/+1 counter Fertilid just spent. You end up draining your entire library of basic lands while generating boundless landfall triggers and mana along the way.