Primal Ice by Ann Gimpel

Renegade dragons. A dying Earth. The magic powering all worlds is fading, and no one knows why.

As the life he’s known for millennia hovers on the brink of ruin, the dragon prince, Konstantin, gathers allies. He would have liked to be better prepared for all-out war, but time grows short. Waiting is no longer an option. Working with his twin sister, a seer, he unearths a shocking sequence of prophecies. Visions that shake the foundations of everything he believed was true.
Newly created dragon shifters, Johan and Erin, are on a supernatural fast-track. No longer human, they have yet to fully embrace their magical sides. Knowledge can only be gained so fast, but if they don’t ditch their reservations, they’ll be swallowed by darkness.
Seduced by a madman, driven by greed, wicked creatures have become bold. Shifters, Sidhe, and land-linked magic are determined to crush the threat eager to steal their power, but even their combined forces might not be enough to bail them out.