So, I have been going back and forth on what I would like my 4th (and final) 40k army to be. It's a very tough decision.
My most recent idea that has been overtaking my thoughts is a Wych Cult themed Dark Eldar list. My plan consists 4 Raiders full of Wyches to get stuck in and rape, backed up by Ravagers and some Trueborn laying down Dark Light fire. The Duke will, of course, be distributing his array of exotic drugs to his harlots.
But there are so many other ideas I have floating in my head. I am really trying to figure out a cool army theme that is pretty good as well. It doesn't need to be super awesome; it just needs to be fun.