Abyssalisks are a species of semi-reptilian, semi-mammalian planar abominations native to extra-dimensional planes of existence such as hyperspace, chronospace and quasi-space. They are a distantly related to dragons, although dragons are extremely fearful of them. They are oviparous, laying clutches of eggs which vary in number depending on food availability.

Strong, powerful and fast, abyssalisks rank among the most dangerous creatures known. Their sharp claws and fangs are comparable to the deadliest of dragons and the ether vents located on the spines on their shoulders can fire a variety of magical beams, most notably beams of petrification and instant pain. In addition, while they are not as smart as dragons, they have above human intelligence and are very cunning.

They prefer to stay on in the interdimensional "ocean" of quasi-space due to it having a plentiful supply of ether-rich creatures to prey on. They tend to stay in packs where food is plentiful and/or an "alpha" abyssalisk is present. Abyssalisks rarely appear in material planes unless summoned. While in material planes, abyssalisks will invade large caverns and citadels that offer food and comfort to make their nest. When food is low, abyssalisks tend to prey on one another, which is why abyssalisks on material planes tend to stay by themselves.