The Mu Mystic is a Mu Guardian in need of rescue. He can be found on the Rescue Mu Mystics from Circle mission from Magus Mu'Drakhan.
Once freed from his captors, he must be escorted and taken to the mission exit. At least four waves of Circle followers will try to take him out on the way to the exit, so beware. He must survive if you want to read the Clue he will give you once in the mission' exit.
He spawned as a Pet of the level of the mission owner +1, having the correspondent amount of Hit Points, and a faction of Arachnos.
During the Rescue the Mu Mystics mission the terrified Mystic can be found captured by the Circle followers and he will say the following:
Circle of Thorns Mage: But do not fear. We will not send your soul screaming to the void.
Mu Mystic: Anything, please! Just don't take me from my body!
Circle of Thorns Mage: ...yet.
Circle of Thorns Mage: I don't know if your body will serve, Villain.
Mu Mystic: Villain! Help me, I beg you!
Circle of Thorns Mage: Let us find out.
My Mystic: You've got to get me out of here!
Mu Guardians pulse with the blood of their slaughtered ancestors in their veins. They have read unholy tomes, visited other planes of existence, and performed dark sacrifices too terrible to mention to become masters of the mystic arts.
During my mission, he used the typical powers of a Mu Guardian: (Please note that this is a guess: I never saw him actually use Touch of the Storm or Sentinel of Lightning. I saw him use the rest, though, and being escorting him a mission objective I didn't want to put him in much danger)
Ball Lightning (Ranged), Targeted Area of Effect, Energy, Foe -Endurance
Hurls a highly charged ball of lightning that explodes on contact. Ball Lightning deals good damage in an area and also drains some endurance from each target it hits.