Mordrak is a real standout unit in the Grey Knight Codex, a real boon to all old and new Grey Knight players alike. There is nothing quite like him in any other codex, and everything about Mordrak really clicks for me: from the fluff perspective (vengeful, haunted Knight of Mortain out to get his arch-nemesis, Huron, with psychic manifestations of his guilt / actual ghosts?), rules perspective (Ghostly Bodyguard for the win!) the gameplay perspective (First to the Fray and Grand Strategy really appeal to the Deep Striker in me!), and most importantly for me, the modelling perspective.
Modelling perspective? But wait, GW hasn’t released actual models for Mordrak. Perhaps during the 2nd wave?