The wording on the card seems a little confusing to me, but I think I get the idea now after reading other posts here.
Maybe try rewording it to something like: "Sacrifice an aether creatures. Enemy creatures take damage equal to the sacrificed creature's cost +2."
That would be a little more clear.
You don't need to use "sacrifice one of your..." since sacrifice mechanic implies that the target is a creature you own automatically (it saves a bit of precious text space on the card that way)
The concept is interesting though. It gives aether some very ugly CC potential. I'm surprised it hasn't been done yet.
The artwork is very cool by the way.