Fiendlash + Boros Reckoner

Prerequisites

You have a way to deal damage to Boros Reckoner.

Steps

1. Deal damage to Boros Reckoner
2. Fiendlash and Boros Reckoner trigger.
3. Resolve the Boros Reckoner trigger, dealing damage to any target
4. Resolve the Boros Reckoner trigger, dealing at least 1 damage to itself.
5. Repeat from step 2.