Toph, the First Metalbender + Magistrate's Scepter + Rootpath Purifier + Earthcraft

Toph, the First Metalbender

Magistrate's Scepter

Rootpath Purifier

Earthcraft

How it works

1. Activate Magistrate's Scepter's first ability by paying 4 and tapping it, putting a charge counter on it.
2. Activate Earthcraft by tapping a creature, untapping Magistrate's Scepter as it is a basic land due to Toph and Rootpath Purifier.
3. Repeat from step 1 two additional times.
4. Activate Magistrate's Scepter's second ability by tapping it and removing three charge counters from it, causing you to take an extra turn after this one.
5. Repeat each turn.

By turning all of your nontoken artifacts into lands with Toph, the First Metalbender and making those lands basic with Rootpath Purifier, you open the door for Earthcraft to treat your artifacts like basic lands that can be untapped by tapping a creature. This clever synergy allows Magistrate's Scepter to be repeatedly untapped to easily accumulate the charge counters needed for its second ability, granting you infinite turns.