Basalt Monolith, The Blackstaff of Waterdeep, and Heartstone

Prerequisites

• Basalt Monolith on the battlefield
• The Blackstaff of Waterdeep on the battlefield
• Heartstone on the battlefield
• Basalt Monolith does not have summoning sickness
• available

Steps

1. Activate The Blackstaff of Waterdeep by paying and tapping it, causing Basalt Monolith to become an artifact creature
2. Activate Basalt Monolith's first ability by tapping it, adding
3. Activate Basalt Monolith's last ability by paying , untapping it
4. Repeat from step 2

Results

• Infinite colorless mana