The Skull Wyrm is a magically reanimated skeleton, thus, is composed almost entirely of bone with severely decayed ligaments and wing membranes lingering, preserved mostly by the extreme cold of its "home". It is approximately 60 feet in length from its snout to its tail, with a wingspan of about 80 feet. The membranes of its wings are decayed and fragile, accounting for the innumerable holes and tears. Despite this, it can still fly by magical means. It has a large amount of fractures in its skull, shoulder blades, and right femur, suggesting a violent but prolonged death. Long, sharp spikes run down its vertebrae starting at the base of the head, but these abruptly end between the wings, the remaining length of the skeleton showing evidence of these spikes having been snapped off. Despite the battered and worn appearance of the skeleton as a whole, the dragon's claws and teeth remain very sharp, and appear to be impervious to damage.
The Skull Wyrm appears to be sentient and is actively hostile. It will seek out any human life and destory it, often targeting living dragons as well. It has not been observed to speak or make any noise, nor does it appear to need to feed, but it will attack large prey(namely the aforementioned dragons) tear at it with its teeth while the target is still alive, appearing to make swallowing motions despite the meat falling through the base of its skull. The target usually dies on the scene, or escapes and dies several days later of acute infection. The Skull Wyrm appears to completely disregard its own self-preservation to the point of flying straight into another dragon's fire or a blast of magic from a skilled mage. The only thing it will do to protect itself is use its tattered wings as a shield, or very rarely fly out of the way of an attack. In the rare case that the Skull Wyrm is trapped, it will remain alert but relatively docile, watching its captor intently until any flaw in its imprisonment is spotted. It will then take full advantage of this flaw and attempt to destroy its former captor.
The Skull Wyrm is found exclusively in Ethanol. While it is usually flying around the ruins of a castle in the northern, mountainous area, it can sometimes be seen in the southern half of the continent, presumably to find food despite not needing it.
Other than being mostly invulnerable to magical damage(it can still be harmed by blunt force), the Skull Wyrm appears to possess formidable regenerative qualities, reforming itself quickly after an attack has shattered part of its body or separated two bones from each other. It does not have a venomous bite, but bacteria from rotting flesh(preserved by the cold of the environment) can and will create a fatal infection in most bite victims that don't die of blood loss on the way. The Skull Wyrm is highly resistant to mind control, but not completely immune; however, the one case where a skilled Dracomancer(much to his initial astonishment) managed to bind the Skull Wyrm to himself, within the hour he was driven insane from what appeared to be acute mental strain and the turmoil within the Skull Wyrm's own mind. He quickly lost control of the entity and was killed immediately after the Skull Wyrm was freed. Despite being a Firedrake, the Skull Wyrm has no apparent affinity with fire, but is completely resistant to heat and cold.