Infernal Tempest is great as well. I'm rather partial to the crusade though. I had large contigents of the Demon Knights running all over my enemies as my last game as Lanka. In Dom2 I had Pazuzu(?) (The demon lord of the plague wind) leading a decent core of the Storm Demons as Abysia and they were very handy, but the knights have been more effective for me overall. Admittedly, that's like comparing really awesome to very awesome.
