Any number of 0 power creatures get to go along for the ride, including creatures that enter with +1/+1 counters and many clones. Seems fair. Though at 7 mana it could probably return all your creatures and not be busted.

This is just the indatha ultimatum, but single colored.

Edit: Nevermind, I confused it with the mutate a tan creature. Nethroi.

Another card that combos with Scourge of the Skyclaves? Sounds interesting.

(Negative power creatures have a fun property of, well, being negative power when calculating total power. Having a high life total means you can bring back your whole GY as long as you bring back the scourge too.)