Dark Elves (?)

Elves twisted with dark magic.

Background
The Dark Elves are ruled by (Unnamed King), who is a master of dark magic.

Hundreds of years ago an elf king betrayed his kingdom by selling out his hold to the orcs, after he was nearly killed by the orcs and shunned by his own people for his betrayal he retreated to the mountains. The king discovered a cave, upon exploration he discovered the entrance to the kingdom of a long dead race.

Exploring its vast halls he came across a vault that had a magic seal, however the seal was fading and he broke it easily. Inside the vault he discovered a sword and a book on a pedestal, upon closer inspection of the sord and book he saw they were in an old dark form of elvish. While he couldn't read most of it some of the letters were similar to elvish, he gathered that the sword was that of the king and that he transferred his magic into it. Upon picking up the sword he felt a rush of pain and was transformed into a dark beast, he was flooded with power and knowledge of the power that used to reside in the long dead kingdom.