Blossoming Tortoise + Deserted Temple + Rings of Brighthearth + Tectonic Split

Blossoming Tortoise

Deserted Temple

Rings of Brighthearth

Tectonic Split

How it works

1. Activate a land by tapping it, adding three mana of any color due to the ability given to it by Tectonic Split.
2. Activate Deserted Temple's second ability by tapping it, targeting the land
3. Rings of Brighthearth triggers, causing you to pay 2 to copy Deserted Temple's ability, targeting Deserted Temple.
4. Resolve both Deserted Temple abilities, untapping Deserted Temple and the other land
5. Repeat