The Final Battle
The Darkbringer will join the battle but not as a party member.
Go back to the central area to fight the ember Goddess.
Keep on the offensive when the fight begins. Don't stick your characters together too much.
When you whittle her health down a bit, she will begin draining the life out of one of the leaders. Attack the Absorption Shield to break it and stop the Goddess from healing.
When the Absorption Shield breaks, continue on the assault on the Goddess.
Around halfway in the fight, the ember Goddess will use a new attack. Similar to what you saw in the battle with the Necromancer and his White Ember Abomination. Move away from this to avoid serious damage to your characters.
She will once again drain one of the leaders of their life. Break the shield once again.
Fight her again and she will attempt to drain the life of the last leader. Break the last shield.
She will now become more aggressive, no longer bound in the center of the map, but keep hammering on her to finally get her down.
Now that you have defeated the Goddess, the last choice the game has you make is about to present itself. The choice of you sacrificing yourself to stop the Goddess, or Fia to sacrifice herself to stop the Goddess.
The choice is purely a different movie that plays at the ending. If you can, reload your save and beat the ember Goddess again and choose the other option to see the other ending.
Thank you for playing ember!!