Supreme ghosteater

SUPREME GHOSTEATER
Huge Aberration
Always Chaotic Neutral
Solitary
Treasure: None
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Occasionally, a ghosteater that has devoured a large number of ghosts—and other incorporeal creatures—evolves into a formidable monstrosity. These supreme ghosteaters appear in vast crypts, on ancient battlefields, or in abandoned necropolises, where the wandering souls they feed upon are abundant. Although its presence might be seen as a blessing, it doesn't make the place it has cleansed of all spectral presence any more hospitable. In fact, many heroes would rather face a few undead, even intangible ones, than confront such a mastodont. Moreover, this monster cares little whether its next meal is an evil spirit, or, on the contrary, the protective ghost of a sacred crypt.
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A supreme ghosteater stands almost 20 ft. tall and weights between 1100 and 1300 pounds in its material form. It generally resembles a common ghosteater, with two thick rudimentary legs and arms, and a mouth full of teeth. But where its former appearance only had a few nodules on its back (containing its previous victims in the process of digestion), the supreme ghosteater is almost entirely covered in large protuberances resembling spectral faces. These ghostly "cysts" sometimes move, slowly sliding across the monster's body and moaning continuously, making the whole thing particularly terrifying. The creature neither speaks nor communicates, although the faces on its body may utter fragments of sentences—intelligible or not—in various languages.
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Dozens of long filaments, resembling wisps of vapor, surround its body and float lightly, as if they were underwater or moved by a gentle breeze. These are actually the monster's sensory organs, allowing it to "sense" any intangible creature within a 330 ft. radius around it, both in the material and ethereal planes. As for other physical objects, including living beings, its senses are extremely dulled, and it can only detect them within 6,5 ft.
These tentacles, which remain intangible even when the creature switches back to its material form, act in a similar way to those of a jellyfish or anemone. Any immaterial or ethereal entity that becomes trapped in them might end up paralyzed, while its essence is slowly drained as long as it remains attached. Detaching from the filaments requires a complex action, similar to freeing oneself from a giant spider web or a net. When the victim has no more energy, it is absorbed into the monster's body in the form of a new cyst.
The supreme ghosteater partially heals itself each time it absorbs or devours an ethereal creature. If the souls it has devoured possessed supernatural powers or spells, the monster can call upon them and cast them by itself. The effects, however, are completely random, as if it had access to the wild magic domain.
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BEHAVIOR
A supreme ghosteater spends most of its time in its ethereal form, invisible and undetectable. Although it roams the ethereal plane to hunt, it sometimes appears in the material plane if something intrigues it. Occasionally, but rarely, it seems to materialize involuntarily in its intangible form—or, even more rarely, in its material form. The idea that such a beast could suddenly appear is enough to discourage most living beings from entering its territory. Its body emits a faint glow when intangible, but it can remain completely silent if it wants to do so. Unlike most intangible creatures, it is unable to fly or even float above the ground: it can still obviously pass through solid vertical surfaces like walls or doors, but always seems to "walk" on the ground, even though its passage does not affect the solid objects it passes through.
When it physically materializes, its goal is usually to get rid of a troublesome opponent by brute force; that is, any individual who resists its spells, or proves themselve capable of harming it when intangible. In this form, it behaves somehow as if it were still immaterial and will barely consider any obstacles in its path, including walls or doors. Given the monster's massive build, few things can withstand its destructive charge anyway.
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Its unpredictability, combined with all its unique characteristics, can make encounters quite complex to apprehend. Furthermore, despite their ghostly appearance, ghosteaters are not undead and are therefore unaffected by clerics' attempts to rebuke or control them, for example. Unscrupulous spellcasters, such as malevolent necromancers, usually resort to summoning or creating incorporeal undead in order to lure the beast to another location, either to draw it away from their lair (at least for a time) or by charging for their services (at an exorbitant price). In the latter case, the monster remains absent for a few days while the reward is collected and the individual leaves the area, before the creature returns to its hunting grounds. The victims of such scams are, at best, unsympathetic, and at worst, hostile towards their potential saviors.