A few weeks ago we introduced you to Lord Marrow (Lord Marrowgar) (see Strategy guide) with a more skeletal and "old" skin, but yesterday we could see that this head of The Frozen Throne has undergone an aesthetic change in the PTR.
Recall that the (now new) skin of Lord Marrow It was already presented a couple of weeks ago (by then, it was unknown if this texture was a boss or a new creature) and that compared to then, if we look at it, it has received some graphic improvement, and added a blue aura.
As a curiosity let us remember He fought 3 weeks ago for the Cuties Only guild on the PTR, and let's compare it to the Impervious Stormreaver guild yesterday.