Aside from what other cards can do, with the card starting out as a black card, I also see no reason to have it be a color-changer. Most people will not use color specific cards unless they have a way to change the color (Slights, Mind Bends, etc...) and to me, black is the best color to have overall on the table cause then you are safe from "...target nonblack creature" which is a lot more common than any other non-color creature. Not so sure about the Regeneration though. Would be handy against direct damage, but not in combat since you can gain pro-any critter with a 2 mana tap. What about some of the older abilities, flying, trample, (considering the name of the card itself ...)banding? But I do like the card and the idea behind it. Overall...kudos to you!