Blazing Sunsteel, and Boros Reckoner

Prerequisites

• Blazing Sunsteel on the battlefield
• Boros Reckoner on the battlefield

Steps

1. Deal damage to Boros Reckoner
2. Boros Reckoner and Blazing Sunsteel trigger
3. Resolve the Boros Reckoner trigger, dealing damage to any target
4. Resolve the Blazing Sunsteel trigger, dealing damage to Boros Reckoner
5. Repeat from step 2

Results

• Infinite damage