Aboleth

An Aboleth is a monster found in various Dungeons & Dragons editions, starting with Advanced Dungeons & Dragons 1st edition, printed in 1981. large, intelligent, subterranean fish seemingly related to a hagfish. They are very rare but ancient, and detest the surface world.

2nd Edition
The aboleth is an amphibious creature that dwells in underground lakes and caverns. Intelligent, it hates most land-going life and seeks methods to enslave or destroy the beings of the surface world. The race is extremely long-lived and has collected a great deal of knowledge more ancient than man. It is perhaps better that men do not know these ancient secrets, for these are rumored to be more horrible and foul than could be thought possible.

An aboleth has a slime covered fish-like body with a large fluke-like tail which propels it through the water. It has a blue-green mottled gray in color with a pinkish tan belly. It has blue-black slime-producing organs on either side. Set in its head are 3 long, slit-like, purple-red eyes, one above the other. Over the eyes are protective ridges. Four 10-foot long tentacles grow from the top of its head, and its toothless mouth is located on the underside. On land, an aboleth pulls its obscene mass about with its 4 tentacles.

In combat the aboleth attacks with its 4 tentacles for 1-6 points of damage each. Any creature struck by its tentacles must save vs. spells or the creature's skin will change into a clear, slimy membrane in 2-5 rounds. This change can be stopped if a cure disease spell is cast on the victim. Once the change is complete, the membrane must be kept damp with cool water or the victim will take 1-12 points of damage each turn because of intense pain. A cure serious wounds spell will change the membrane back to normal skin.

The aboleth is highly intelligent and can create very realistic illusions with audible and visual components if it concentrates and does nothing else. It can also try to enslave other creatures 3 times per day. This ability can be used only against a single creature up to 30 feet away. The victim must save vs. spells or be filled with desire to serve the aboleth. Enslaved creatures will not fight for the aboleth but will attempt to follow any other telepathic commands. If an enslaved character is separated from the aboleth by more than a mile, a new saving throw may be made each day. This charm can be broken by remove curse or dispel magic spells or the death of the enslaving aboleth.

In water, an aboleth will secrete a cloud of mucus a distance of 1 foot all around its body. Any creature drawn into the mucus must save vs. poison or it will inhale the stuff and be unable to breathe air, suffocating in 2-12 rounds if it tries to breathe. However, the aboleth uses its mucus to give its slaves the power to breathe water. Thus, its slaves will have the ability to breath water, as a potion of water breathing, for 1-3 hours. The mucus may be dissolved by soap or wine.

There are reports of huge underwater cities built by the aboleths those they enslaved. But these reports, along with the stories of their vast stores of knowledge, have never been proven.