His name is a fusion of two roots. The first being the Old English þorn (thorn), which is related to the german „Dorn“ and the second being „torn“ (see: to be torn; to tear from *teran, Old German zeran, zehren) that is to say, being ripped or destroyed.

Yes he is a mortal being just like you, but he’s using enchantments and spells to exceed his human limits. His mask is also enchanted and works as an amulet.