Im in a very How to train your dragon mood, so what better time to talk about a few fan species?
Invisidons are flightless, pack hunting dragons, named for their ability to go invisible at a moments notice. They are blindingly fast, and are capable of killing a man merely by ramming into them, if their powerful jaws dont get to them first. Their fire is similar to the night furys, only pure white instead of purple, which they use to blast down trees as they pursue their prey.
I first thought of putting them in mystery class, because of the colour changing, but the more I thought about it, the more it kinda fits strike class. Its got the speed, they hunt in coordinated packs so decent intelligence, their firepower is just a white plasma blast, they even have powerful jaws, which are supposedly a defining trait of the class even though none of them have it. And since night and light furies can both go invisible aswell, it all works out.