I don't see a problem. Darkness has Parasite that uses Death Quanta. Creatures other than Air can be Airborne. Death creatures gain a power boost from Eclipse (why does a skeleton get more powerful cause its dark?). Its a cross relationship, not a mutually exclusive environment.
That makes slightly more sense, as Darkness and Death are good friends. However, Darkness does not have the ability to control death and unlife; it is not capable of holding a soul inside a corpse and creating an undead creature. And again, look at the art of Vampire; perhaps "Vampire Bat" is a more suitable name.
As for the card itself... The CPU might go crazy if your opponent casts Rain of Fire on a field of Skeletons, since you draw a card for every undead creature killed. I suggest removing the draw card part, to increase the chance of it severely backfiring on you; if you don't want that, then I think you need to increase the cost a bit.
Have you tested this card in your simulation?
