The Underworld Cookbook, Clock of Omens, Metalwork Colossus, and Primal Vigor

Prerequisites

• The Underworld Cookbook on the battlefield
• Clock of Omens on the battlefield
• Metalwork Colossus in hand
• Primal Vigor on the battlefield

Steps

1. Activate The Underworld Cookbook's first ability by tapping it and discarding Metalwork Colossus, creating two Food tokens
2. Activate Clock of Omens by tapping the Foods, untapping The Underworld Cookbook
3. Activate Metalwork Colossus by sacrificing the Foods, returning it from your graveyard to your hand
4. Repeat

Results

• Infinite self-discard triggers