Dragon Age Inquisition: Side quests - Therinfal Redoubt Dragon Age: Inquisition Guide

There is only one side quest available in Therinfal Redoubt - Demonic Dogma. You should complete it the very first time you have a chance to (while you're exploring further parts of the nightmare) - you won't be able to return to this location later in the game and you won't have another chance to complete this quest (and hi is very well rewarded).