Voltaic Construct, Karn, Silver Golem, and Prismatic Geoscope

Prerequisites

• Voltaic Construct on the battlefield
• Karn, Silver Golem on the battlefield
• Prismatic Geoscope on the battlefield
• available

Steps

1. Animate Prismatic Geoscope using Karn
2. Activate Prismatic Geoscope by tapping it, adding at least three mana of any color Activate Voltaic Construct by paying , untapping Prismatic Geoscope
3. Repeat from step 2

Results

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