Return to Thassarian at the Scarlet Tavern in New Avalon with news of your victory.
Return to Thassarian at the Scarlet Tavern and let him know that Koltira's cry for vengeance has been answered. The Chapel of the Crimson Flame will be a pile of ashes in a matter of hours.
You're one cold-blooded monster, <name>. I salute you, brother.