The Mercurial Menace is a distant relative of the ordinary wyvern. Albeit aside from the shape of its silhouette similarities quickly end.
The reflective skin of the Mercurial Menace does not only provide an ample physical protection, but it also shrouds the fast moving flyer with a shroud of irritating light reflections that can confuse opponents and let many attacks only hit thin air. Yet this additional protection comes with added weight that makes airborne manoeuvres vastly more difficult and the Mercurial Menace quickly becomes hard pressed to maintain greater heights even if needed.
There seems to be a yet to be discovered island at some remote spot in the gnomerean seas, where they return to breed and raise their young. This somewhat seem to restrict them to certain areas of Gnomprona and stop them from spreading too far. As the Mercurial Menaces seems to spend only little time there at all such a place is probably some inhospitable yet safe piece of rock.
Their seemingly erratic movement and attack patterns add to the confusion, which is one of the most dangerous tools of this flying predator. It moves swiftly, attacks, retreats a little only to attack again in the next moment. Added with the slightly blinding effects of their skin, the Mercurial Menace seems to shift places within a blink.
Their constant chirping that rather reminds one of crickets than any bird, mammal or lizard, adds to the confusion that they spread. Another sound they employ is closely resembling those of the local shrieking crystals, which might be some form of acoustic mimicry that adds to their tools of distraction and confusion. It's of note that this chirping or acoustic mimicry only starts when the Mercurial Menace is already attacking and it can approach its target with almost any noise, trying to attack by surprise.
Despite being skilled, though not enduring flyers they tend to roam close to the grounds and rather fly through thickets then to fly over it. That might be to avoid the arial superiority of the numerous nighthunters that roam the upper layers of gnompronean airspace.
Mercurial Menaces have 18500 hitpoints. They are immune to holy damage and cannot be paralysed. Moreover, they are strong against fire, ice and physical damage. On the other hand, they are weak against death, earth and energy damage. These creatures can neither be summoned nor convinced. In addition, they are able to sense invisible creatures.
Mercurial Menaces yield 12095 experience points. They carry crystal coins, mercurial wings and sometimes other items with them.