After reading exterminatus I want to try out the following list.
Lord of war:
-Seth.
HQ:
-Librarian.
Elite:
-9 death company - 2 power swords, powerfist.
-Death company dread - claws.
Troop:
-5 man tac squad - heavy flamer, rhino.
Fast:
-3 x 5 assault squad - rhino, 2 melta guns.
Heavy:
-2 Baal preds.
-Stormraven.
Total points: 1500
Probably not as good as detachment out of main codex. But it's cool and I have the models for it. Two rolls on flesh tearer warlord trait and a small chance for my models to have rage. Also can take one troop and up to six assault choices. I belive I still get furious charge as well but I know I loose +1 initiative.
If the army plays ok I might just keep it as my core and add to it. Extra units would likely be taken from fast attack to take advantage of the detachment. Perhaps a bike squad or some heavy flamer landspeaders. I should take at least one assault squad in a drop pod.
Yet to have time for a game but I can finish up painting this army. Should not take too long. Base death company and storm raven models. Add weapon bits and finish painting infantry.