Aboleth

Ancient beyond mortal understanding, aboleths are aquatic aberrations who can be found in bodies of water across the multiverse. These enormous eel-like creatures grow to be about 20 feet long and weigh up to 6,500 lbs. 
As one of the oldest, or perhaps the oldest, sentient lifeform in the planes, aboleths are alien creatures who have flawless and eternal memories. They pass on their ancient knowledge and experiences perfectly from generation to generation. This eternal perspective allows them to plot across eons and recall pieces of forgotten, prehistoric lore with prestine clarity. that have some sort of natural link to the Elemental Plane of Water. When slain, an aboleth will reform out of raw ectoplasm in the Plane of Water. 

Eternal Memories

Aboleths have flawless memories. They pass on their knowledge and experience from generation to generation. Thus, the injury of their defeat by the gods remains perfectly preserved in their minds.
Aboleths’ minds are treasure troves of ancient lore, recalling moments from prehistory with perfect clarity. They plot patiently and intricately across eons. Few creatures can conceive of the extent of an aboleth’s plan.

Gods in the Lake

Aboleths dwell in watery environments, including ocean abysses, deep lakes, and the Elemental Plane of Water. In these domains and the lands that adjoin them, aboleths are like gods, demanding worship and obedience from their subjects. When they consume other creatures, aboleths add the knowledge and experiences of their prey to their eternal memories.
Aboleths use their telepathic powers to read the minds of creatures and know their desires. An aboleth uses this knowledge to gain a creature’s loyalty, promising to fulfill such wants in exchange for obedience. Within its lair, the aboleth can further use its powers to override senses, granting creatures, such as its followers, the illusion of promised rewards.

Enemies of the Gods

The aboleths’ fall from power is written in stark clarity on their flawless memories, for aboleths never truly die. If an aboleth’s body is destroyed, its spirit returns to the Elemental Plane of Water, where a new body coalesces for it over days or months.
Ultimately, aboleths dream of overthrowing the gods and regaining control of the world. Aboleths have had untold eons to plot and to prepare their plans for perfect execution.

Abilities

Like many other denizens of the Far Realm, all aboleths have great innate psionic powers. They can telepathically speak with other creatures and psychologically probe them to learn their desires. Using these desires, the aboleth will often then enslave creatures. Once enslaved in this way, the creatures can be slowly psychologically drained until their psionic energy has been utterly consumed by the aboleth.
They also secrete a psionically charged viscous gray fluid, similar to a mucus. When this fluid comes in contact with terrestrial creatures, a horrible transformation occurs. The creature's skin is temporarily transformed into a thin membrane that allows it to breath underwater, but also requires it to be constantly hydrated. Creatures that are kept in this state for long periods of time are slowly transformed into the alien Skum.

Aboleths of Faerûn

Beneath the deepest drow cities of the Underdark, and even beneath the deep mines of the dwarves, there lies the ancient depths; a sprawling collection of steaming, tropical jungles of phosphorescent fungi who feed off the toxic volcanic fumes that fill the air and vast subterranean lakes filled with eye-less fish and horrific . In the depths of these bodies of water, there are vast