Basalt Monolith, Heartstone, and Karn, the Great Creator

Prerequisites

• Basalt Monolith on the battlefield
• Heartstone on the battlefield
• Karn, the Great Creator on the battlefield
• Basalt Monolith does not have summoning sickness

Steps

1. Activate Karn's first loyalty ability, causing Basalt Monolith to become an artifact creature until end of turn
2. Activate Basalt Monolith's first ability by tapping it, adding
3. Activate Basalt's Monolith's last ability by paying , untapping it
4. Repeat

Results

• Infinite colorless mana