There's only one mounted Dark Elf sorceress and she is riding the least used mount ever for a sorceress, a Cold One. A Manticore is a pretty rare mount too I guess, but Cold One is just bad. So you have to make your own sorceress on a Dark Steed if you want the best out of your points invested in Dark Magic. Since most of the spells in Dark Magic are short ranged you have to get in close fast. I built the cloak of Green Stuff that I draped over 2 long metal wires that I drilled holes for in her back. Pretty simple actually. The sorceress torso is from an old Witch Elf Hero, the one that rides on the beautiful old Dark Pegasus. I just cut off her enormous hair and let the cloak go up over her head. The hips and legs are from a 5th ed Cold One knight. The right hand is from a 6th ed Warrior sprue, the sculls the horse is standing on is from the Hellcannon. After a visit at the barber shop.