|Pic Unrelated but awesome|
Nayuki, one of the FiM layout artists who hangs out on the Allspark Forum, dropped some clarification on the new villain's name. Head on down past the break for it to avoid any spoilers!
Apparently it is actually "Sombra" not "Somber". Meghan McCarthy also confirmed this on her Twitter page.
Thanks to everyone that sent it in!