Zirda, the Dawnwaker, Omen Hawker, and Crab Umbra

Prerequisites

• Zirda, the Dawnwaker on the battlefield
• Omen Hawker on the battlefield
• Crab Umbra on the battlefield
• Omen Hawker does not have summoning sickness

Steps

1. Activate Omen Hawker by tapping it, adding that can only be spent to activate abilities
2. Activate Crab Umbra by paying , untapping Omen Hawker
3. Repeat

Results

• Infinite colorless mana that can only be spent to activate abilities