Will do.

Edit; Le done. Looks good to me. The things LeeRoy pointed out is spot on. The only thing I would like to add, is that on the "Power of the underworld" - you specify the size of the darkness. As "Darkening the battlefield" is a bit too vague, seeing as every battle location is of varying size and shape.

As for it being magical darkness, and allowing only people who specifically see through magical darkness to see through it; I was uncertain if I wanted to allow such a powerful ability, but seeing as it takes you three preps to get there, and that the ability strongly hints your opponent way ahead of time as to what it does, I'm gonna give it the go-ahead. Once the size of it is specified, that is.