Since there is not a model for Mordrak on the market yet, I decided to go with Scibor and make a Mordrak conversion. I already bought some bases from them a while ago, but wanted a miniature that would stand out from the crowd, so decided to use one from Scibor's Roman Legionary range.
The body of the miniature is resin and stands up well to close inspection. There is one minor air bubble in the hair of the miniature, but it isn't noticible really. And I think that an undercoat (perhaps slightly thick in just the one area) will actually disguise it without having to resort to greenstuff. The arms, shoulder pads and weapons are, of course, from the grey knights terminators boxed set that I used to create some of my other ghost knights from earlier. The overall vibe of the miniature is good -- the scibor model has just the right hint of haunted-ness about him, coupled with the agressive avenger look and ornate armour that may befit a grand master. Alternatively, this miniature could alwyas be used as an Ordo Malleus inquisitor in terminator armour if I decide to make a Mordrak out of regular grey knight bits and pieces.
Although I could probably convert up a regular grey knight if a tournament organizer objected to this miniature, I hope that they wouldn't. I think this guy looks pretty cool and contains approximately 50% games workshop parts by volume (and 5/6's by bits! -- hahaha!). The only other thing that I'm considering doing is to add an iron halo just behind Mordrak's head. I don't know whether to use bits for that or attempt a greenstuff sculpt by hand.