Springbloom Druid + Springheart Nantuko + Horizon Explorer

Springbloom Druid

Springheart Nantuko

Horizon Explorer

How it works

1. Play a land.
2. When the land enters, Springheart Nantuko triggers, causing you to pay 1 to create a token copy of Springbloom Druid.
3. When the Springbloom Druid token enters, it triggers, causing you to sacrifice a land, then search your library for a basic Forest and another basic land and put them onto the battlefield untapped due to Horizon Explorer
4. When the basic lands enter, Springheart Nantuko triggers twice.
5. Holding priority, activate both lands by tapping them, adding 1.
6. Resolve the first Springheart Nantuko trigger, choosing not to pay and creating a 1/1 Insect creature token.
7. Resolve the second Springheart Nantuko trigger, causing you to pay 1 to create a token copy of Springbloom Druid.
8. Repeat from step 3 until your library contains no basic lands.