So the Mark of the Wulfen upgrade that I can put in one of my Grey Hunters, Blood Claws or Wolf Guard Units. The dude in the unit that has the mark replaces the number of attacks he normally has with D6+1 attacks with rending. If someone has a special weapon (fist, claws etc.) the special rules for the weapon are not used. This is still frigging awesome. I have charged a sole survivor with the mark into a full squad of Tau fire warriors and wiped them out.

For the modeling side of this, I wanted to get a box of the 13th Company Wulfen from the old 3rd ed mini-dex Eye of Terror. These minis are pretty cool and show the fluff of the model. It says that the marked Space Wolf has shunned the use of any close combat weapons and is clawing at his opponent.