A deadly threat on Karasuthra and, to a lesser degree, Brux, the aeserpent (also known as darkstrike or deathstrike) is a deadly predator that lurks the darkest areas of the Beastlands. Many think this snake to be in some way vampiric or magical, but this animal is purely natural, simply ravenously efficient at hunting.
This beast is thought by some sages to originate from a plane other than the Beastlands — a natural assumption given the Beastlands' nature. Though some suspect the Lower Planes on first impression, the lack of an evil nature to the aeserpent makes this an unlikely possibility. The theory given most credence is that the aeserpent was of some prime world but was (likely) hunted to extinction due to the extreme danger of the species, leaving them only in the Beastlands; while it's possible that they in fact do exist on some yet-lost Prime, they've never been reported anywhere outside the Outer.
The aeserpent is a massive snake, reaching fully 20 feet long in adulthood, covered with a deep black skin interrupted only by its glowing yellow eyes. Preferring the darkness where they find themselves most at home, aeserpents can be found in most parts of Karasuthra, and rarely in the darkest sections of Brux, lurking in the grey mists of that layer.
These snakes are most often found alone, though they occasionally will be encountered in mated pairs. Aeserpents mate for life, and are fervently protective of one another. Mated aeserpents will gain a +1 morale bonus to attack and damage when fighting together. Further, they're fairly clever for animals, quite able to lure even humanoids into ambushes or traps and often exploiting the natural landscape to arrange an encounter with quicksand, landslides, or other such hazards. After having mated, the female aeserpent will lay a small clutch of up to 8 eggs after about 8 weeks' time, which the two animals protect as devotedly as one another. After the eggs hatch, however, the newborn aeserpents are abandoned to make their way on their own; as aeserpents are not territorial, there is little conflict between parent and child after the latter reach maturity.
- Planes of Conflict - Monstrous Supplement, pp. 2-3