Voltaic Construct + Silverskin Armor + Viridian Joiner

Voltaic Construct

Silverskin Armor

Viridian Joiner

How it works

1. Activate Viridian Joiner by tapping it, adding at least 3.
2. Activate Voltaic Construct by paying 2, untapping Viridian Joiner.
3. Repeat

This classic two-card loop relies on a clever type-shift to turn a mana elf into an infinite battery, and Silverskin Armor is the secret ingredient that makes it all possible. By turning Viridian Joiner into an artifact creature with the Armor, it becomes a valid target for Voltaic Construct's untap ability. Once the Joiner's power is high enough to produce more than the two mana required to untap it—which happens naturally as it grows—you can repeatedly tap for a surplus of green mana and untap it indefinitely.