On Nightmare difficulty, this battle is the first test of your ability to micromanage and manipulate the Tactical Camera. The highest challenge demands it throughout the game, regardless of your build, and especially here when your resources are limited to whatever potions you managed to save. To prepare, use none of the potions you obtained at the Forward Camp between the chosen route and the temple itself. Instead, warriors should rely on Guard and Barrier to preserve their health and keep rogues and mages out of any danger. The route you choose has no effect on your support, but the mountain route has more enemies and thus more opportunity to take damage.
The demon will start by powering up its Guard, becoming virtually invulnerable to damage. The Inquisitor should immediately disrupt the rift (takes about 5-7 seconds with zero interruptions) to remove the pride demon's guard. The demon spends a great deal of time posturing and laughing at the very beginning of battle, providing a perfect window of opportunity to disrupt the rift. Solas should cast Barrier on the group while it is still clustered, then move to a point far back, preferably where an archer is stationed in the back corner, as well as Varric. From here, Solas can use Winter's Grasp to weaken the demon, and Varric can maximize the damage on his Long Shot talent. Make sure to click the 'Move to Point' location twice so they will 'Hold Position' at that point. Otherwise they may elect to come back down and close the gap with the enemy, which not only puts them in greater danger but may allow the Pride Demon to damage more allies with fewer attacks. Since he can take off half a health bar with one lightning attack, keeping your team spread out is the first priority. Cassandra should engage up close and keep boosting her Guard. Under manual control one can tap Shield Wall between attacks to conserve stamina while still raising Guard, but the AI manages just fine. If Solas and Varric are staying out of trouble, only Cassandra and perhaps the Inquisitor will need health potions. Solas will use Barrier automatically, but under manual control, try to get as many people in its Area of Effect as possible, with priority going to Cassandra and the Inquisitor.
After its initial posturing, the demon will start off to the right-hand side, in the direction of an Elite-ranked Soldier. Continue to assault the demon until it raises its Guard once more (around 11000 HP remaining). Do not abuse the rift, or you may end up powering up the Demon and summoning his backup yourself, who will immediately assault the Inquisitor! Always allow the demon to bring up its own guard before using the rift. At this point, two shades will join the fight, each with about 1000 HP. Do not leave it to your warrior(s) to fight them alone while the ranged allies waste their shots on a guarded Pride Demon. Bring up the Tactical Camera, move Solas and Varric back if they've advanced too close to the front lines, and command them to attack the same shade as the Inquisitor. This combined assault will eliminate the shade in a few seconds, allowing a similar approach for the second. The next step is to manually control the Inquisitor and shake off the Pride Demon, who will very likely recognize them as the biggest threat, despite the angry woman with a shield smacking a sword against its shins. Circle the central column evading the demon's lightning as best you can, until you can get yourself 7 seconds to spare closing the rift again (which is easier said than done, it's all about getting rid of the Threat you've generated by allowing others to become more threatening, such as Cassandra, Leliana, and the soldiers who accompanied you to this fight).
When the rift is successfully disrupted, the demon will be stunned. Instead of fighting the demon, use this opportunity to revive any fallen allies (including Leliana, who, while not a party member, will join you in this fight and will fully recover without the need for a Healing Potion, making her a valuable assistant) and use Healing Potions. Remembering to keep Varric and Solas back, repeat the process as the demon's health keeps sinking. Eventually his Guard will go back up and two more shades will join, and with enough practice you'll be able to manage. Eliminate the shades as before and disrupt the rift. Remember that only the Inquisitor can disrupt the rift; if they fall in battle, someone will have to risk their own skin to revive them while the demon bares down.
Two-to-three disruptions will be enough to defeat the boss, as the demon ends up with 3000 HP left and doesn't repeat the Guard phase beyond this point. Outlast his attacks (again, easiest with Solas and Varric out of harm's way) and eventually he'll fall.
The Inquisitor Edit
The strategy will change significantly depending on the class and weapon choice of the Inquisitor, as the abilities granted to the Inquisitor are predetermined (with one possible exception) and can make or break a crucial stage of the fight, which involves disrupting the Fade rift to remove the Pride Demon's guard:
A Mage Inquisitor has Flashfire and Chain Lightning for starting abilities. Flashfire consumes a great deal of mana and only strikes a single target, but Pride Demons are vulnerable to Fear effects, which despite its short shelf life (the effect ends upon being hit) can interrupt their deadliest attacks entirely. Save it for when the demon holds its hands out and builds lightning, as it is charging its overhead slam attack (which can kill anything in its linear area-of-effect (AoE). Chain Lightning can affect multiple enemies, but with friendly fire enabled can behave unpredictably, particularly in this fight. Add the Pride Demon's Electricity resistance and it's not a good idea to use, so ignore it and save all mana for Flashfire. Keep the mage Inquisitor at mid-range, close enough that Flashfire will connect in time but far enough that most of its attacks will not come close. They can be upgraded with Barrier at the level up to provide backup for Solas' Barrier, or Fade Step to evade the Pride Demon's most lethal attacks.
The rogue Inquisitors have Stealth, which will make evading the demon and its backup a trifle. Simply remain in Stealth during the demon's guard phase until Cassandra has its full attention, then disrupt the rift. Use Stealth in conjunction with Twin Fangs/Long Shot for additional damage, and use Twin Fangs/Long Shot in conjunction with Solas' Winter's Grasp for Shatter combos on Frozen shades. For the level up, you can take either Evasion or Easy to Miss to build upon its evasive advantage, or upgrade your starting ability for even more damage (with Long Shot able to hit the Pride Demon and its shade backup with little effort).
A Weapon and Shield Warrior Inquisitor has the best defensive potential in the game, and it shows during this fight. Use Shield Wall to build Guard and resist the demon's attacks, breaking away only to disrupt the rift. Taunting abilities should be avoided as it will draw the enemy to keep attacking, and the lightest infliction of damage will instantly end any attempt to disrupt the rift.
The Two-Handed Warrior Inquisitor likely has the most difficulty in this fight. They lack the obvious advantages of the other four possible builds (ranged attacks of mages, evasion of rogues, defense of Weapon and Shield warrior), and Mighty Blow is a slow attack with a large hitbox, a fatal hazard with friendly fire enabled at this early stage of the game. They can trigger Shatter combos on the Shades in conjunction with Solas' Winter's Grasp, but it is a small consolation considering a better use for Winter's Grasp is Chilling the Pride Demon to reduce the frequency of its attacks. One of the best abilities to get for them at the game's first level up is Charging Bull, which grants a means of high-speed escape from the enemy while building Guard off any enemy with which they collide.
- Disrupting the rift right before the shades spawn will kill them instantly. However, this can be very difficult to time and even requires anticipating their arrival, when all attention should be kept on the battlefield and the Pride Demon.