Quote Originally Posted by Iscah View Post
From memory, Phoenix changes colour after we defeat and un-temper it/him.
Quote Originally Posted by Rocl View Post
Phoenix actually changes colour after the add phase in the battle during the Final Coil of Bahamut. Once Phoenix finishes casting the "Rebirth" skill and enters the final phases of the fight, its blue feathers turn the red-orange. It's the latter colour in Unending Coil as well, but I'm not sure you can confidently point that "blue feather = tempered" when Louiphoenix still pounds away with us at full force in the actual canonical encounter of Final Coil as the red-gold Phoenix.
In fact, Phoenix changes BACK into red-blue after we beat him. The red-gold is just more of a 'high-powered' state if anything. And yes, according to Flames of Truth, he doesn't transform, but his aetherial shroud assumes a phoenix like shape before it bursts through Teraflare.