Donna Noble, and Boros Reckoner

Prerequisites

• Donna Noble on the battlefield
• Boros Reckoner on the battlefield
• Donna Noble is paired with Boros Reckoner
• You have a way to give Boros Reckoner indestructible
• You have a way to deal damage to Boros Reckoner

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