Frost Dragon

So far, we know of two Frost Dragons. Reina and her unnamed Father.  (Chapter 507: None Shall Escape) 

"Frost Dragons belonged to a branch of the Elemental Dragons. As their name suggested, they were blessed in the field of ice and every adult Frost Dragon was a Great Master in the ice element. Especially in an environment like (the Winter Plane), they could display the pinnacle of ice magic ".

The most useful part of a Frost Dragon's corpse is its' Frost Dragon Crystal. "If a mage obtained a Frost Dragon Crystal, the immediate priority would definitely be to embed it into their magic staff. Using that magic staff to cast ice spells would increase the mage’s understanding over the Law of Ice at an unimaginable speed over time".

(Chapter 508: What Makes You Think I Don’t Dare?)

"Frost Dragons weren’t very eye-catching among the Dragon Race. Compared to those pure-blooded Chromatic Dragons, there was some gap in their innate talents. For example, once a Pure-blooded Chromatic Dragon reached adulthood, they would have the power of a Heaven Rank powerhouses. In contrast, Frost Dragons were quite inferior. They were only comparable to Archmages when they reached adulthood ".