It's a dark grey. When I painted my Warlock I did a basecoat of black, drybrushed with an old Ral Partha color called Drow Flesh (I think the Reaper analog is Shadow Grey). Then I did highlights with grey a shade lighter than than the Drow Flesh.
But I never saw the Crusade ep where the Warlock was shown, don't know if that was official, but it did match my Omegas :wink: