So, Zero to Tentacles on the Greater Daemons of the four Chaos Gods?
(Lore tldr, there's a dimension made of psychic energy and emotions ruled by four evil gods that each embody specific emotions/thoughts. We never see depictions of the actual gods, but they each have Greater Daemons said to be made in their images, and we see a lot of those)
First is a Bloodthirster, Greater Daemon of Khorne (The Blood God, embodies war, violence, rage, bloodshed). Essentially a rage-fueled murder machine, but also smart enough to be tactically brilliant in a fight.
Next, a Lord of Change, Greater Daemon of Tzeench (God of Change, magic, and scheming). Powerful psychic wielders of magic, able to see potential and actual futures, comparatively physically weaker than the other Greater Daemons, but with the strongest magic. Also their forms are constantly shifting and changing.
Third, a Great Unclean One, Greater Daemon of Nurgle (the Plaguefather, god of disease, stagnation, decay, and life). Lumbering and titanic masses of rot, filth, and disease, they have an incongruously jovial demeanor as they see themselves as bringers of gifts and blessings (the gifts and blessings are disease!)
And finally, a Keeper of Secrets, Greater Daemon of Slaanesh (She who Thirsts, the Dark Prince, god of excess, obsession, decadence, and sensation). Think a combination of a dominatrix succubus/incubus, mixed with a shoulder devil whispering to you to indulge your worst impulses and desires until you end up like something out of Hellraiser
(this ended up being long, sorry 😅)
Eh... All these youngins putting me to work, *grumble grumble*...
In all seriousness, let's take a look:
Bloodthirster - Is this where the phrase 'blood for the blood god' originates from? Anywho, looking at this design really brings to mind the Deathclaws from Fallout. However, on a scale of appreciation... Definitely filling me with 'I can fix him/*Spoiler Alert: She, in fact, could not fix him' energy.
Lord of Change - See, I was about to say that I was vibing with this design (obligate love of a blue color-scheme) but then you mentioned that their forms are constantly changing so it's like... I can't really appreciate your design if it isn't static. In regards to the picture example, though, I like the draconic aspects though I will say the face is giving Skeksis from The Dark Crystal. Just expecting this fellow to start going 'Hmm!'
Great Unclean One - Well, that... Sure is a design. I like the idea of them being jovial despite their good tidings being full of plague, but... Yeah, not for me.
Keeper of Secreta - Ah, yes, I've heard of this Slaanesh figure in conversation... But, back to this design. Admittedly this is very much my wheelhouse: otherworldly entities that still maintain some method of sensuality. Very nice.
All in all -- the Unclean One notwithstanding -- all very strong designs. Definitely gave me some insight on the fascination with this universe.