A Toa of Light, turned to Shadow.
Originally, Xiroc was an ordinary Av-Matoran in Karda Nui. When the Makuta invaded, however, he became a Toa, and was trained as a sniper. However, soon into the fight, he killed a Shadow Matoran, largely in self-defense, and was exiled from the forces. Enraged, he turned to Makuta - who was unaware that he killed a Shadow Matoran - gaining the element of shadow, and seeking revenge on those who exiled him.
That backstory was't great, I know.
I must say, I believe this to be one of my best mocs. It will most likely be displayed at several of the remaining Lego conventions this year, including Brickfair VA.
Sorry about the bad pics.
Thanks for the mask, JMJ.
Edited by SmoothJazz, Jan 15 2014 - 11:26 PM.