Sydri, Galvanic Genius, Voltaic Construct, and Grim Monolith

Prerequisites

• Sydri, Galvanic Genius on the battlefield
• Voltaic Construct on the battlefield
• Grim Monolith on the battlefield
• Grim Monolith does not have summoning sickness
• available

Steps

1. Activate Sydri by paying , causing Grim Monolith to become an artifact creature until end of turn
2. Activate Grim Monolith by tapping it, adding
3. Activate Voltaic Construct by paying , untapping Grim Monolith
4. Repeat from step 2

Results

• Infinite colorless mana