Dragon's Fire: Novellas 4,5, & 6

Sometimes, even four dragons aren't enough.

Frozen Flames
A new Unseen, creature of darkness, roams the city. As the dragons attack it in their usual fashion, they soon find themselves in deeper than they expected. This creature dodges their attacks and winds up testing the strength of the group.

Draco Ex Machina
With two members of their team gone, the dragons must call upon the help of the elder dragons. When Thane arrives, he seems more of a liability than a help. The elder dragons show up and help restore order to the group once more - with a warning.

Circle of Flames
The large Unseen continues attacking those within the city, imitating them to get its way. It will only be through the concentrated efforts of the entire team that they'll get this creature into a prison. If they fail, the entire city will fall.