Ensoul Artifact, Grim Monolith, and Biomancer's Familiar

Prerequisites

• Ensoul Artifact on the battlefield
• Grim Monolith on the battlefield
• Biomancer's Familiar on the battlefield
• Ensoul Artifact attached to Grim Monolith
• Grim Monolith does not have summoning sickness

Steps

1. Activate Grim Monolith's first ability by tapping it, adding
2. Activate Grim Monolith's second ability by paying , untapping it
3. Repeat

Results

• Infinite colorless mana