Well, I bit the bullet and got shot of the Destroyer Lord - He'll have to wait for another game.
Instead, I have added a heavily tricked-out Overlord with all sorts of goodies, a unit of Lychguard, and we've upped the points so I can include 6 Wraiths and two Ghost Arks.
I think I'm going to win this, must just blow the living daylights out of the inevitable Bloodletter horde...