I use the new Russ Grey, wash with a 50/50 mix of Druchii Violet and Aggrax(whatever replaced Devlan Mud), highlighted with Administratum Grey, final highlight using 50/50 mix of Administratum Grey/white. It has changed a bit over the years given all of the formula changes from GW paints, but the overall approach has been the same for me since 3rd edition.
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"Solutions are good, how many dark eldar archons can you find sitting in their throne rooms whining that they used to rule the universe? Exactly." -The Burning Eye
Splintermind: The Dark Eldar Podcast
My Dark Eldar Project Log