Leviathans looked very similar to normal kuo-toa, with a bloated body, spindly limbs, flat, webbed extremities, and silvery scales. The primary difference was their immense size, being four times as tall and weighing 125 times as much as normal members of their kind. Their massive maws were filled with various rows of needle-like teeth seemingly big enough to swallow a horse.
Kuo-toa leviathans slowly swam through underwater caverns waiting for any unsuspecting creatures to devour. They had no qualms about eating other members of their kind although few kuo-toa were privileged enough to meet with one.
Leviathans almost never attempted to exit the water, preferring the advantage they held within its depths. Their enclave of kuo-toan servants would distract more fearsome targets as it picked off prey one at a time. They possessed all the abilities of normal kuo-toa, enhanced by its massive size. So great was their mass that they were capable of swallowing several humans whole and digesting most within a matter of seconds. Even if one managed to cut their way out of a leviathan's stomach, their muscular actions could seal the wound later on, forcing a new path to be cut immediately after. The blessing of the Sea Mother also granted them a kind of sixth sense allowing them to dodge blows even if caught off guard.
The destructive monstrosities known as the kuo-toa leviathans were not born so much as made. Talented kuo-toa whips and monitors could receive the blessing of the Sea Mother herself and grow to gargantuan proportions. Leviathans were venerated by non-clerical kuo-toa who wished to attain such importance in the eyes of their goddess. They were usually placed in positions of power over lesser kuo-toa without priestly abilities of their own, like whips, monitors, and regular kuo-toa, but only a small assortment of about twenty.