Shadowmantle

The Shadowmantle is a wild, cavern-dwelling monster akin to a huge, land-walking manta ray. Its starfish-like body is covered in placoid scales, and its boneless wings enable it to glide through the air or cling to surfaces. Shadowmantle are scavenging carnivores that prefer dark, wet places to hide in, and shrink from natural light. Their bodies can expel an inky substance per the spell Shadowstuff, which they use to weave traps out of. Their white underbellies conceal a tiny maw framed by two beady red eyes, ever thirsty for plasma. When a Shadowmantle strikes, it engulfs its prey whole with its wings and sups on their blood to replenish its health. It can also impale victims with a long caudal spine it retracts from its body. Worse of all, the Shadowmantle can emit a subsonic moan that reverberates through the bones of those in a melee area of effect, effecting the sound maleficence even if they are unable to hear it.

Ultimately, Shadowmantle are animals, even if eldritch in appearance. On the battlefield, they operate in colonies as disorienting controllers, until they can peel off single adventurers from the group to envelop and consume. Use the creature’s ability to generate Shadowstuff or produce Mirror Images of itself as a way to augment its concealment and lure in reckless PCs, but keep in mind that all its illusory abilities are mundanely caused by the effects of its sonic moan on its victims’ minds. Thus, a PC who manages to mitigate that aura becomes immune. Finally, natural light is a Shadowmantle’s bane: bright sources dispel their Shadowstuff and cause them to flee in panic.