Apparition (Spellhold)

The Apparition creatures are several non-player actors for the Asylum plot and associated with the final tests needed to navigate the Escaping the asylum questline.
== Gameplay ==
These apparitions, also called "Arbiter" in the game files are Undead spirits of some type that still fulfill the mechanisms of evaluating inmates of the Spellhold asylum. Frankly, this isn't explained very well in the game, but it really isn't a mystery that has to be solved in order to progress through the various tests and hurdles to be freed from the asylum discharge process.
There is a total of fifteen different .CRE files associated with the apparition appearances in the game. Many of these will only be produced based on dialogue choices made when the party is replying to questions from the Arbiter. Different tests have separate .CRE files and dialogue trees. 
In general, the more non-compliant and combative or uncooperative the party is with the Arbiters, the longer it will take to get through the tests presented by these arbiters. In many instances being recalcitrant or unaccepting of their orders results in additional remedial challenges and tests. However, further tests provide more gameplay, and a way to gain further experience and even some loot.
These creatures are not meant to be attacked or faced in combat. They are designed to be immune to this sort of hostile action for plot purposes. It may be possible to actually cast a spell or fire a missile weapon at some of these creatures, but it won't gain any advantage and is really a waste of energy. Although difficult to do, breaking the game script will result in a reload scenario, so don't purposely foul up the game cohesion.