Voltaic Construct, Karn, the Great Creator, and Arc Reactor

Prerequisites

• Voltaic Construct on the battlefield
• Karn, the Great Creator on the battlefield
• Arc Reactor on the battlefield

Steps

1. Animate Arc Reactor using Karn, the Great Creator
2. Activate Arc Reactor by tapping it, adding Activate Voltaic Construct by paying , untapping Arc Reactor
3. Repeat from step 2

Results

• Infinite colorless mana
• Infinite untap of artifact creatures you control