Yea, the Klavex should have come with the PGL to entice people to take him. As it stands, almost everyone suggestions just taking 4-7 incubi and that's all. The other things just don't pull their own weight.
So you're really left to using Wyches as the tarpits and sending Incubi in to clear the assault so they can attack at initiative, or giving them an archon with pgl with a venom blade or something like that for a premium.
Shame Drazhar didn't come with one. Really puts the breaks on him when joining a squad too.