I'd drop a Horror and a Bloodletter to upgrade those Soul Grinders to DoN. And be forewarned: though a blob of daemonettes seems intimidating, they vanish to enemy shooting fast.
I would drop whatever you need to in order to put Karanak in those Bloodletters: to Scout them forward, to give them great anti-psyker defense and offence--even to sprint him to the front of the unit when you're about to assault for those extra few inches of range. He has no AP or rending, so he's not too impressive against a hardened target, sure, but... in terms of synergy and anti-psychic capability, he's worth it for that alone. (That I stick him in a squad with a banner to lock down Skarbrand's DSing for no scatter, myself, is just another plus).
I'd say to get those points... start with dropping 2 of the Fiends and the other 12th Horror, then... probably the Alluress w/ Etherblade (she's a tempting squad leader, but I find my Alluresses tend to get squeezed out in the list-making process)... hmm. Maybe also a Screamer?
I'd also go for dropping the bonus ML from the Warlord in favor of a second Greater Reward. The survivability they can offer is unparalleled.
Looks pretty good and fast, though! If you weren't spending quite so many points on An'ggrath (say, were fielding Skarbrand instead) I'd advise you also take a winged Slaaneshi DP for the better anti-air (with a Lash and a shot at Iron Arm), but as is... looks fine!
What sphinx of plascrete and adamantium bashed open their skulls and ate up their brains and imagination? Imperator! Imperator!