I'd suggest working a bit more on the head- The skull mas right now looks like its resting over his nose with the maw proturing a bit. Ingame will not be that easy to spot, but the portrait might be a bit too silly. Also why so many dark colors? Tzeentch is rather colorful to denote change, I think you can try some other textures on the model, maybe a faceless one and see what the weird textuures can give to it. Right now I think thats your weakest one at the moment, still can be useful tho.
He resembles Bloodletter (face), Keeper of Secrets (horns) and Lord of Change (colour) at the same time.
Perhaps the Greater daemon of Chaos Undivided?
Well done anyway; I'll probably use him in campaign somewhere (already like the models for my upcoming DOC).
Looks quite amazing! Looking forward to see more chaos warhammer related stuff! Slaanesh (must be), Khorne and Nurgle! I hope you do it! This guys tho... Look amazing (Sorry, my fandom for warhammer realms is too great!) :'D
That staff on Ahriman the Exile... is it supposed to move like that?
I need some good chaos sorcerer models, and I think Ahriman would be perfect either without the staff, or while holding it with a different animation.
And again I am lucky to have old versions of these models! Of course, some of the new ones look much better, but some of them look completely different and can not be used in the same way as the old ones (such as War Wagon, for example).