Marvin, Murderous Mimic, Horseshoe Crab, and Sanctum Weaver

Prerequisites

• Marvin, Murderous Mimic on the battlefield
• Horseshoe Crab on the battlefield
• Sanctum Weaver on the battlefield
• You control at least two enchantments
• Marvin does not have summoning sickness

Steps

1. Activate Marvin using Sanctum Weaver's ability by tapping it, adding at least
2. Activate Marvin using Horseshoe Crab's ability by paying , untapping it
3. Repeat

Results

• Infinite colored mana