The Cultist is an enemy in The Consuming Shadow.
Description
Robed humans who worship the Ancients and have some knowledge of runes and spells. They are found within dungeons and often drop loot when killed. They are the only human enemies in the game, and the only enemies (other than the Ancient his/her/itself) that actively uses magic.
Despite being human, they are either immune to the attacks of more monstrous creatures or are simply never targeted by them. However, they are never found on the same screen as any other enemy, so perhaps they are no more welcome in the dungeons than the player character. Doubtless, they will most likely be slaughtered along with the rest of humanity should the Ancient succeed in its invasion; it is highly unlikely that the god they worship even knows they exist, let alone cares.
It can be safely assumed that when not prowling around actively servicing the Shadow by casting spells and being nuisances, that they are also the ones carrying out the abductions that are frequently referred to in the in-game notes found in dungeons. After all, it's a vitally important job and someone has to do it. No otherworldly invasion is complete without an accompanying rash of ritual sacrifices that will, naturally, go entirely unnoticed by the cosmic entity in question. But it gives the cultists something to do, and that's always nice.
Tips for fighting
The Cultist will attempt to cast a spell by chanting two runes. To fight it, wait for the the runes to appear on-screen, then quickly enter the spell screen (which pauses the game so rushing is not necessary) and then cast the same runes. The runes you cast will appear on screen, and should overlay the ones cast by the cultist; if they do not, you've messed up and now have both Sanity loss as well as health loss to deal with. Should you successfully cast the correct runes, the Cultist's shield will drop which allows the player to shoot or hit him.
Since the Cultist dies in one melee hit at default melee damage, it's recommended that no bullets be used to kill them. If one must be used (the player may be playing as the Wizard), use as cheap a bullet as possible.
When a Cultist's shield is down, they will walk up close to the player. This can be useful if attempting to kill them with a melee strike, however if shooting (the player may be playing as the Wizard), it's possible that the reach of the player will pass through the Cultist and waste a precious bullet.
In-game description
The Ancients are not entirely forgotten by this world. There are, among humans, deranged cultists who have prepared for their return in secret before record-keeping began. They have sacrificed their sanity for power, and have an almost instinctive grasp of rune incentation, using their god's wicked magic to shield themselves from harm and fire death-dealing offensive spells. However, their magic is base and second-hand, and a rival magic user can easily dispel their efforts by incanting their own mantras back at them. This wil cancel out all magical effects, leaving the (often physically frail) cultist utterly defenseless.
Logbook
If the player character dies against it, their Logbook entry will begin with, "Killed by a hostile magic spell".