The thing about this army is that it looks like the only unit that can really hold its weight in combat is the Soul Grinder. Somebody could press home against your 1ksons and Horrors pretty easily--I find that such units work best when supported by somebody who presents a good counter-assault or covering fire threat. AP3 bolts are all well and good, but 1ksons are still pretty inflexible in that marine-killing role: moving like Infantry, dying as easily to light arms fire, quite a bit more expensive, and unable to Overwatch thanks to Slow & Purposeful.
To balance the list a bit more, I'd be tempted to exchange the second unit of 1ksons for cultists and another big heavy hitter--choices that spring off the top of my head are taking a Maulerfiend or upgrading the Herald to a Lord of Change, who really packs a whallop (especially with a Lesser Reward swapped for a Staff of Change and 2 Greater Rewards for defensive buffs!).
If possible, I'd try to get more Mastery Levels on that Sorc, so that it has more utility and flexibility than simply one of your Aspiring Sorcerers (for rather more points), and you're able to roll powers from Telepathy or Biomancy.
Alternately, you could go Daemons core detachment with CSM Allied. 1x 1kson squads, only 1 Forgefiend--but a second Soul Grinder, plus 2 squads of Horrors acting as warp charge banks for the higher ML Sorc and Herald or (preferably) LoC. I don't think you could afford to swap the LoC for Fateweaver for safety against the Warp Storm at this point's level, but... still might be a fun variation that needs minimally different minis.
What sphinx of plascrete and adamantium bashed open their skulls and ate up their brains and imagination? Imperator! Imperator!