Hellkite Charger + Iroh, Dragon of the West

Prerequisites

An opponent cannot block and kill Hellkite Charger.

Steps

1. At the beginning of your combat phase, Iroh triggers, giving Hellkite Charger firebending 2 until end of turn.
2. Declare Hellkite Charger as an attacker, triggering its innate ability and each instance of firebending it has.
3. Resolve all firebending triggers, adding {R}{R} for each trigger.
4. Resolve the other Hellkite Charger trigger, causing you to pay {5}{R}{R} to untap all attacking creatures you control and get an additional combat phase after this one.
5. Repeat each combat phase.