Hmm. I would be tempted to run something with 2 Combined Arms Detachments (dual force org, you know), to bring Lords of Change instead of Daemon Princes where possible. You can cover 4 Troops choices with blocks of 11 Horrors, probably, I think. Or even Nurglings, if you want dirt cheap, essentially Fearless Objective Secured scoring units with Shrouded. Yay for 7e letting swarms score!
I'm also very inclined towards bringing Fateweaver for those vital rerolls and Warp Storm rerolls, if possible, and/or bringing Be'lakor to cast Shrouding so that any of those Tzeentchi DPs within 6" of him can Jink for a rerollable 2+ cover save. I mean, the Nurgle DP's 2+ cover save is all well and nice... but I'd rather have a dude who has a native 2+ and also gives out rerollable 2+es like candy.
Fateweaver+Be'lakor, add in a Grimoire on one of the other Tzeentchi FMCs. A bubble of fast, brutal, almost untouchable killers (one of which Invisible thanks to Be'lakor, probably a Cursed Earth on there...)
What sphinx of plascrete and adamantium bashed open their skulls and ate up their brains and imagination? Imperator! Imperator!