Exorcist

"All know the reputation of the exorcists of Westmarch, those spiritual warriors specialized in removing demonic possession. By custom, they arrive in darkness, clad in cloaks as black as the night that conjured them. They work in secret, extracting the demons that dwell within their subjects. Now Malthael has turned them, and they roam the city in their inhuman forms, stripping the souls from all they encounter."

- Lorath Nahr

Exorcists are part of Malthael's Reaper forces in Diablo III: Reaper of Souls.

In-game
The Exorcists are often hidden when encountered. When they spot the player, they start 'charging up' (visible by their sinister azure glow) and prepare their only attack. When ready, this attack releases a medium-ranged (roughly 35 yards) piercing beam that causes very fast ticks of Lightning damage. Once this beam is created, it may not be stopped or retargeted for 1 second, although while charging it, Exorcists still may aim. It's wise to move away from the monster before they can fully form the attack, but due to the aiming, a simple strafing left or right might not help. In addition, Exorcists may teleport at will.

Before patch 2.4, the Exorcists' aiming was so quick and flawless that it was nearly impossible to dodge their beam without going out of its range.

Malthael summons two Exorcists at his side during his second phase in combat.

Uniques

 * Charok (Sorcerer's Room, Magic Misfire event)
 * Fohsgrave the Usurper (Tustine's Brewery, The Lost Patrol event)
 * Matanzas the Loathsome (Westmarch Commons)
 * Yergacheph (Westmarch Commons)

Development
Conceptually, the Exorcist originally dropped "evil stuff" on the ground that would chase players. However, it was dropped due to its abstract nature.