Manifestations of the Mirage

Six fragments from one being. Six places at once.

These entities behave... abnormally.
They have been encountered in their (for lack of a better term) "glitchy" form twice within the Red Desert, with slightly different behavior each time.

• At first, they would not deal damage directly. Instead, when an entity would hit with its attack, it would apply a stacking debuff on its target, dealing periodic damage and having at least one other effect specific to that entity. The only known viable way to clear such a debuff was to destroy the entity that applied it.
• In the second encounter, their attacks were more powerful: in addition to the same stacking debuff as before, they would also front-load some of their damage right away. Fortunately, the party learned that the debuffs can be cleared with a Remove Curse spell.
• During the third encounter, the entities had grown considerably larger, increasing the range on their attacks and allowing them to hit multiple targets at once within that range.

They also do not receive damage normally. The only known viable way to destroy an entity is to land a successful blow from each of the lightborne weapons that were spawned in the area, though these weapons were only spawned under special circumstances (in the first encounter, this happened when one of the entities was destroyed by a beam of starlight; in the second encounter, each individual's assigned weapon would only spawn when that individual assisted a Statue of Questionable Sentience in the area).
Three of these entities seem to be represented by people in Aeternia:

• The Visionary, having a strong eyeball motif about it, was shown to be dead very shortly after Baxton Mandrim was also killed. Baxton publicly appeared to be missing an eye (and the rest of one side of his face), but during a key encounter, it was revealed that he actually had an incredibly large, warped eye.
• The Gasping Orator, being associated with breath, was seen using a unique ability also possessed by Vicra Lammergeyer, who does not speak. During a key encounter, Doctor Vic took a very painful breath, which seemed to trigger that ability.
• The Eavesdropper, being associated with sound, was represented by Pendel Codagio, who was obsessed with melodies of the Song of Time. During a key encounter, his true form was revealed to be some a bat-like creature with large ears, and his Orrery of the Wanderer would manipulate the tempo of the combat.

Posthumously according to Baxton, Exignis is equally divided into six pieces, each of which is "owned" by someone, presumably the person who represents one of these entities. This seems to have been confirmed by a map of Exignis found in Vicra Lammergeyer's Lair.
Riley Ellasandra believes that "Fogwalker" is another one of the group, as is "Mother Girth".

The Visionary

Appearance: Hollow, covered in hardened nerves and eyeballs.
Known special characteristics: none.
Debuff: unknown.
Represented by: Baxton Mandrim.

The Hemorrhaging Smog

Appearance: entirely gaseous and liquid, despite having a pair of humanoid legs.
Known special characteristics: flight, and can move through other entities.
Debuff: As you are temporarily engulfed by the Hemorrhaging Smog's body (?), you feel hundreds of razor-like bits slashing at your skin, although no damage shows when you exit this smog. You are now poisoned. While the Hemorrhaging Smog is healthy, you are not.
Represented by: unknown.

The Eavesdropper

Appearance: its flaps of flesh vibrate wildly as if resonating with every sound.
Known special characteristics: none.
Debuff: There is a terrifying high-pitched scream that only you seem to hear. The screeching is incredibly painful and does not subside. While the Eavesdropper hears, you will not.
Represented by: Pendel Codagio.

The Gasping Orator

Appearance: every orifice gapes and its rubbery form inflates and deflates like a balloon as it "breathes".
Known special characteristics: none.
Debuff: You feel a terrible tensing of your chest and diaphragm. It is incredibly difficult to breathe, and you worry that if you get hit again, you will not be able to breathe at all. You try to scream out in pain, but nothing comes forth: you cannot muster a single noise. While the Gasping Orator breathes, you will not.
Represented by: Vicra Lammergeyer.

The Lady in Arms

Appearance: countless arms, flowing like a dress through one another before merging with the floor.
Known special characteristics: none.
Debuff: You do not feel the Lady in Arms make contact with you at all. In fact, you can't feel anything, not even your hands. Instead, you just feel a terrible cold and numbness. On a second stack, you can no longer hold anything: your arms are useless. While the Lady in Arms feels, you will not.
Represented by: unknown.

The Skittering Pony

Appearance: many legs that clip through one another as it flits about sporatically. The legs grow and decay contantly, with new legs folding out of it's central mass as older legs wither away.
Known special characteristics: incredibly high movement speed.
Debuff: You feel a terrible crushing sensation in your legs, as if you are being grasped by a terrible beast. You immediately fall prone and take periodic bludgeoning damage. While the Skittering Pony walks, you cannot.
Represented by: unknown.