Hmm I never knew Slaanesh was so popular with you people. Be careful Eldar you just might the same mistake twice.
Drew a quick sketch to add a bit of visual for mine: My power fantasy is the chief librarian of a blood angels successor chapter, wearing white sanguinary-guard stylized armor including the winged jump pack. Equipped with a rather large force-sword and one of those books librarians usually carry around on the hip. The psychic hood is fashioned into the design of a halo, similar to sanguinary guard. As for psychic powers, I imagine having Cleansing Flame, some sort of healing power (that I always imagine working like an apothecary narthecium on the tabletop) and Sanctuary.
An ork that stole a riptide then orkified that thing up! Maybe replace main guns with a combi 4x stolen broadside cannon that fires at proper orky rates and has a jetpack that three times as big and the other arm has a giant gretchin guided missle salvo launcha.