>>96465753
>TQ
Go full Legacy of the Void.
Eldar have a large event where Craftworlds, Exodites, Harlequins, Ynnari, and Dark Eldar come together and deal a major blow to Slaanesh that frees them of being perpetually trapped by the soul thirst. Not a long term alliance; Harlequins. Dark Eldar, and Ynnari break back off afterwards to pursue their own agendas. Exodites and mainly absorbed into the Craftworlds, give'em a Kill Team maybe.
Eldar re-establish themselves as a major power in the galaxy while also acknowledging the mistakes of the Eldar Empire and working to prevent them (even going as far as conflicts with Dark Eldar, who are overtaken by the Haemonculi who wish to re-establish the Old Empire).
Put a significant focus on the actual rivalry between the Eldar and the Necrons as well as with Slaanesh.
And above all have Vect return as a major character and centerpiece, with an audiobook where he's voiced by John de Lancie.