[@Mattie_]

No, it's fine. This setting has a lot of wizards and such, so while invisibility might equal invincibility at first, pretty quickly we'll be facing human armies that can counter that sort of thing.

[@Saarebas] The main character treading the line of being a one-man army is Azavarn. Combining insane speed with equally insane accuracy and the ability to teleport is pushing it. Of course, you could always say that it just takes him a few moments to teleport and that he's exaggerating a bit when he says that he can hit a fly from 300 yards and move so fast that he's a blur :P

Remember, we can't have somebody single handedly defeat an entire army of magical knights and sorcerers.