The latest thing that's been bubbling away in my imagination is the concept of 'Croneworld Eldar'. I know it's sort of skub, but I've rather taken to the idea.
The concept is that a very few of the Eldar who survived past the initial birth-scream of Slaanesh revelled in the destruction of their race and gave themselves completely and willingly to her service (either that or they're a few of the most dedicated and depraved pleasure-cultists who even in her first few moments managed to impress the Prince of Pleasure and were resurrected as favoured pets).
These few corrupted Eldar are formidable psykers, exploring the full potential of their power augmented by the ruinous powers, unfettered by the wards that Farseers use to hide from She-Who-Thirsts.
That would let me explore some of the fluff about what pre-fall Eldar might have been like. To give it a completely different flavour to Craftworlders, Exodites or the True Kin I thought I'd use the Chaos Daemons codex to represent them (with a little added from
CSM).
So, spitballing some ideas for Croneworld Eldar and thought I'd get some feedback
The first aspect of Croneworld culture is the Cronelord.
Cronelord
Fluff: Cronelords are the lords and masters of their daemonic Crone Worlds. These few corrupted Eldar are formidable psykers, exploring the full potential of their power augmented by the ruinous powers, unfettered by the wards that Farseers use to hide from She-Who-Thirsts.
Counts As: Fateweaver/Lord of Change (immensely powerful psyker)
Modelling ideas: big base for a small, eldar-sized model. Minimal armour, maybe just robes. Floating up in the air, with wings like this:
The second aspect of Croneworld culture is the mortal minions

the descendants of the most depraved pleasure cults who are let live as pure amusement for Slaanesh. There are a couple of units I've come up with for these.
Pleasure Cultists
Fluff: The remains of the most dedicated pleasure cultists of the old Eldar Empire. Spared by Slaanesh they live still on a few worlds at the old core of the Eldar empire. Obsessed beyond the point of madness with depraved pleasure and martial splendour they live their immortal lives in constant revelry and slaughter.
Honing their combat skills to perfection they hurl themselves at the ranks of their enemies, rending flesh and armour alike with blades wreathed in fell warp energies.
Counts-As: Daemonettes (T3 and minimal armour, plus WS5 fits the idea of perfectionist
CC Eldar)
Modelling ideas: The good staple Wych legs (love the dynamism), with Dark Elf Corsair front torsos and
OOP Dark Elf Spearmen heads to make them look Eldar, but distinctly different to Craftworlders, Exodites and True Kin. Dark Elf Doomfire Warlock weapons look crooked and warped enough as well. Throw in some Daemonette arms and heads every now and then and voila!
Aethervessels
Fluff: Considered a gift bestowed by their Crone Lord, some Croneworld Cultists are formed into living conduits for the energies of the warp. These hapless individuals unleash great blasts of eldritch energy, annihilating their foes.
Understandably this has a detrimental effect on their martial skills, constantly battling to hold their beings intact as fell energies pour through them into the material world.
Counts-As: Pink Horrors
Modelling ideas: Maybe High Elf archer legs. Doomfire Warlock masks. If the torso from Doomfire Warlocks works I'll use that. If not any suggestions for a bare elf torso I can easily get 10 of?
Favoured Plaything
Fluff: Through their actions, some Cultists gain the favour of She-Who-Thirsts. They are blessed with formidable skill and power, although Slaanesh is a fickle patron. One single stumble and they can be devoured whole.
Counts-As: Herald of Slaanesh
Modelling ideas: Not sure as yet beyond the
OOP fantasy Champion of Slaanesh helmet that I have. Maybe 4 arms?
Croneweaver
Fluff: The Croneweavers are powerful psykers beneath the Crone Lords. Formally a psyker cult dedicated to Morai-Heg in pre-fall Eldar society, as she was devoured by Slaanesh they were cursed by their patron for their part in her demise. Their once-upright stature and lithe bodies were crippled, resulting in the bitter and twisted creatures they are today. For beings so dedicated to beauty and perfection as the Eldar, such a curse would be unbearable. Perhaps that is the reason they persist. A perfect vengeance is sweet in itself.
Counts-As: Herald of Tzeentch
Modelling ideas: I've got this vision of a hunched over, cloaked figure that looks like an old hag or crone. So far I've come up with this which I think captures what I was thinking:
I've even come up with an idea to represent Daemonic Instability
At the Whims of Fickle Gods: Being as they are the transitory playthings of She-Who-Thirsts, the lives of the Croneworld Eldar exist only at her pleasure. As such, they can live and die and live again at the fickle whims of their patron. Even as they charge towards their enemies, a step wrong and a light stumble can be enough to invoke the ire of the Prince of Perfection causing them to drop as a lifeless husk upon the battlefield. Conversely, if their actions somehow please their lord they could find themselves, or her whims simply swing the other way, they could find themselves thrust back onto the mortal coil, rising from their resting place to do the dance of battle oncemore.
Onto the other part of Croneworld Eldar, and the bit that explores their pre-Fall society/technology a little.
During the War in Heaven, the Old Ones created many races to do battle against the dread forces of the C'tan. As the warp was anathema to the C'tan, the Old Ones crafted a race specifically designed to weaponise the considerable power of the warp. That race was the Eldar.
On ancient battlefields long-since forgotten, the early Eldar waged war against the metallic Necrons. Using their formidable psychic might they manifested great warhosts to march alongside their mortal warriors.
In the millenia since the fall, this technology has been lost and forgotten, being suicidal under the gaze of She-Who-Thirsts. The last remaining aspect of this technomancy to remain is the construction of wraithbone, it being energy drawn directly from the warp and solidified. The greatest technomancy of the Eldar, lost. Lost to all but those that remain on the Eldar homeworlds within the Eye of Terror.
These twisted Eldar still raise great hosts of daemonic beings to wage war against their foes, resplendent in the despoiled livery of ages past. The many and varied ancient weapons of the Eldar are known as Aetherconstructs. A few are listed below:
Aetherconstruct 1 (need names for these)
Fluff: These summoned warriors are the basic soldiers of the summoned hosts. Tougher and stronger than any mortal Eldar, and armed with arcane weaponry they are formidable foes.
Counts-As: Noise Marine
Modelling ideas: Sylvaneth Spite Revenants would look really cool painted like daemonic entities. Give them some eldar-ified Noise Marine weaponry and we're away
Aetherconstruct 2 (need names for these)
Fluff: Vicious clawed fiends that can fade in and out of reality at whim, these Aetherconstructs warp into the battlefield and immediately set about rending the enemy limb-from-limb, screaming in eldritch voices.
Counts-As: Warp Talon
Modelling ideas: Just a plain Spite Revenant repainted would be perfect

they've already got 'lightning claws'
Aethercolossus
Fluff: The most mighty of the pre-fall Eldar warp constructs, these towering beings of pure destruction cut great swathes through the battlefield.
Counts-As: Soul Grinder or Daemon Prince, whichever you prefer
Modelling ideas: Drycha Hamadreth
What do you reckon?
The idea that led me to these was thinking about Wraithguard in the context of some fluff I'd read about Eldar summoning constructs to do the heavy-lifting in their empire/fight the War in Heaven.
What if these warrior constructs of old were simply wraithbone shells that they summoned a daemon into (back when the warp wasn't the hellscape it is now and they were more compliant). This technology developed into the Wraithguard necromancy when they discovered that Eldar souls could power these constructs as well.