Not to steal Upinthe's thunder, but I have an idea for a Wrath effect:
Unmake
5WW
Instant
Destroy all creatures that did not come into play this turn. They can’t be regenerated.
Rout can be played as an instant for 5WW. I'll see what people think first, but if this is really bad I could go with a more conservative:
Unmake
3WW
Sorcery
Destroy all creatures that did not come into play this turn. They can’t be regenerated.