Alkilith

Alkiliths were among the few denizens of the Abyss that even other demons found revolting. Disgusting and terrifying, these tanar'ri resembled a bright green mass of dripping, toxic corruption.

Description
Alkiliths had an ooze-like green phosphorescent body, dotted in swollen eye-globules. It was covered in a leathery coating that constantly cracked open, oozed, and hardened again. While normal alkiliths were about human-sized, they could alter their form to fit archways or cracks, and they could be easily mistaken for strange fungal growths if they remained still. Some were known to take on an alternate form in the shape of a green cloud of vile vapor. It was believed that there was no upper limit to the size they could grow, and there were reports of a lake-sized specimen in the deepest layers of the Abyss.

Personality
Alkiliths were hateful creatures that took pleasure in polluting their environment. This desire was so extreme that they were willing to ignore attacks against them for the chance of corrupting a fresh body of water

Abilities
Alkiliths could move surprisingly fast despite the gelatinous nature of their bodies, and could squeeze through cracks as small as one inch wide. They could strike out at their enemies using several of their acidic pseudopods, causing frailer foes and fragile items to degrade from the clinging ooze.

They were known to host a large number of magical abilities, most of which furthered their mission to cause pollution and decay, such as contagion, desecrate, enervation, stinking cloud, at will and unholy blight up to three times a day. detect magic, dispel magic, hold monster, magic circle against good, wall of ice, teleport without error and cone of cold were also in their magical skillset, with the lattermost spell only usable three times a day. They were capable of summoning a hezrou to aid them in a battle if need be, and were also capable of controlling oozes.

When donning their cloud forms akilith were so noxious that they affected other beings similarly to a cloudkill spell, while they themselves were immune to harmful gases in any state. Bludgeoning them in particularly was ineffective due to their amorphous bodies. The very presence of a alklilith was a bad omen of things to come, as it spread madness around itself causing a faint buzzing noise to appear in people's minds and cause them increasingly confusion. In fact an akilith could even corrode the fabric of reality, growing themselves around apertures like doors and windows in order to become living gates to the Abyss.

Society
Alkiliths were considered so hideous and horrifying, even by demonic standards, that other demons loathed, and feared their presence. They were often sent by demon lords to complete tasks in regions of the Abyss they would thrive in where other demons found too inhospitable. Their ability to create gateways to the Abyss made them often too risky for many cultists to consider summoning, forcing them to make their way to the Material Plane on their own.

Alkiliths were both the servants and children of Ghaunadaur, who often used these creatures to carry out his demands. They formed from the stray pieces that Ghaunadaur left behind as he moved, gradually growing and gaining increased self awareness before setting out to spoil the world. Alkiliths could be summoned by a very powerful thrall of Juiblex despite the fact it would normally exceed their regular demon summoning capabilities.