Voltaic Construct, Coveted Jewel, and Tough Cookie

Prerequisites

• Voltaic Construct on the battlefield
• Coveted Jewel on the battlefield
• Tough Cookie on the battlefield
• Coveted Jewel does not have summoning sickness
• available

Steps

1. Activate Tough Cookie's first ability by paying , causing Coveted Jewel to become an artifact creature until end of turn
2. Activate Coveted Jewel by tapping it, adding three mana of any one color
3. Activate Voltaic Construct by paying , untapping Coveted Jewel
4. Repeat from step 2

Results

• Infinite colored mana