Donna Noble, and Boros Reckoner

Prerequisites

• Donna Noble on the battlefield
• Boros Reckoner on the battlefield
• undefined

Steps

1. Give Boros Reckoner indestructible, if needed, and then deal damage to it
2. Donna Noble and Boros Reckoner trigger
3. Resolve the Donna Noble trigger, dealing that much damage to an opponent
4. Resolve the Boros Reckoner trigger, dealing that much damage to itself
5. Repeat from step 2

Results

• Infinite damage