Earthcraft + Fertile Ground + Morphling

Earthcraft

Fertile Ground

Morphling

How it works

1. Activate the basic land with Fertile Ground attached by tapping it, adding at least 1.
2. Fertile Ground triggers, adding .
3. Activate Earthcraft by tapping Morphling, untapping the basic land.
4. Activate Morphling's first ability by paying , untapping it.
5. Repeat.
6. If the basic land is an Island, you may add mana of any color using Fertile Ground's trigger, and you may infinitely repeat steps 3-4 with any other basic land you control.