The Deathwing Redemption Force is a formation in the new DA codex. Technically, as a formation, it can be stand alone. I don't remember how many slots it has on its force org, but I'd bet it's playable as something like 1500 points.
With that said, there are NO Deathwing options that start on the board turn 1, they all force you to deploy from deep strike, so you can't legally play Just that.
Editor's Note: That's not entirely true. I have been reminded that all of the Deathwing options allow venerable dreadnoughts in drop pods. Drop Pods say that 1/2 can come in first turn. So technically, you DO have something that drops in first turn... but those units could easily get tabled by an opposing force.