Arcane horror

Arcane horror is created when a pride demon takes control of a mage corpse. Although they appear to be little more than bones, these are fierce creatures, possessing not only all the spellcasting abilities of a living mage, but also the capacity to heal and even command other animated corpses.

Locations
(Mage Asunder)

Abilities
Arcane horrors have three types and one unique boss, and like party members have conditions for Combat Tactics:

Loot
(Lower Ruins)
 * Some gems

Strategy
Arcane horrors are easily killed, but have very high damage output. When they are immediately attacked, they are easily dispatched, but left alone they will devastate a party. It is a good idea to ignore other enemies and attack the arcane horror first.

In a party with ranged attacks, it's possible to kill the demon without it even damaging the party. In a party with a mage, using spells that drain mana like Mana Cleanse, Mana Clash, or Mana Drain can severely inhibit the arcane horror, especially when used in the improved drain Spell Combo.

When fighting the arcane horror in the Werewolf Lair, it is easy to kill it swiftly if you can get all party members a ranged weapon (either a bow or a staff), and keep them on the stairs above the arcane horror. Make sure to have hold position on however.


 * 1) All four party members must stay near the door.
 * 2) Send one of them, an animated dead, or a summoned wolf near arcane horror and immediately run with it to the party. The arcane horror will attack that party member with spells like paralyze, weakness, or etc., and a horde of undead will follow.
 * 3) After killing the undead, the arcane horror changes his position and you can target him from the stairs.

Alternate strategy: 1. Kill off the minions around the horror. 2. Select whole party and then move em way back up on the stairs or so, this sometimes drags the Arcane Horror to follow you there. 3. Now away from the platform-like thingies, the arcane horror is unable to teleport, making him an easy target.

Locations

 * One in the Danarius's Manor during Bait and Switch in Act 1
 * One guarding the altar atop Sundermount during Long Way Home in Act 1
 * One in the Ruined Passage during Magistrate's Orders in Act 1
 * One in the Underground Passage underneath Harimann Estate, during Repentance in Act 2
 * One "frost horror" variation during Mirror Image in Act 2
 * One "sky horror" variation during The Cult of the Sky in Mark of the Assassin DLC.

Abilities

 * Exhaustion
 * Spirit Shield
 * Spirit Bolt
 * Teleport

Elemental resistances

 * Cold: Very weak
 * Electricity: Very weak
 * Fire: Normal
 * Nature: Very weak
 * Spirit: Normal, or immune on Nightmare mode

Strategy
In the sequel, the arcane horror is every bit as dangerous, if not more.

On the attack, it has three spells with short cooldowns. Against characters who are clustered together, it will use an area of effect spell that damages and stuns everyone. On Hard and Nightmare it deals enough damage to kill even tanks at over 95% magic resistance in a single cast, making killing the arcane horror a priority. Since you are stunned you don't get the chance to move out of the area, so it is advised to keep your party spread out so that it can not kill more than person at once.

If melee attackers are sent against it, the arcane horror will launch a spell that emits a very bright blue light and does massive spirit damage that can easily take down a tank in mere seconds. Unless your characters have heavy spirit resistance such as that afforded by a Rune of Spirit Warding, they should use this opportunity to flee. One positive side effect of this is that while this counter-melee spell is active, the arcane horror is immobilized so ranged characters can get some free shots at it.

Lastly, it will sometimes use a knockback spell that sends a member of your team (typically a mage) flying, but does very little damage. Fortunately, all three spells require two or three seconds to activate: this is represented visually by the arcane horror spinning its arms. This gives the player a very short but crucial window to interrupt its spellcasting using certain abilities and spells, e.g. Winter Grasp or Pinning Shot.

To fight an arcane horror, one tactic is to try to make it Brittle (since it has low physical resistance) and thus vulnerable to follow up with Archer's Lance.

Sundermount
If you play as a mage, one simple tactic is to have a party of Varric, Merrill and Fenris. Lock the party's position at the bend below the clearing where the Arcane Horror waits. Select Fenris and run up the path to lure the Arcane Horror to the upper bend and then run back down. Your party will automatically attack. The Arcane Horror will then teleport back to its original position. Lure it again and auto attack. When the Shades appear, lure them and attack them as they move down the path.

Lure the Arcane Horror as many times as needed, though 3-4 times should be enough before it dies. If done right, no party member will die, or even need healing.