I thought it clearly said only those listed mobs can you level the crystals off so no other mobs would it work with. No one does Zaken cause the combination of waiting for the time to get to 12:00 and the crit error that happens with the door opening and not enough time to log back in before ti closes just make it pointless to even organize.
My alliance killed Zaken about 2 weeks ago but I don't think we tried to level crystals off him either. Unlike Antharas, where you can make sure one group gets the final hit, Zaken is much more chaotic and unorganized (at least when we did it LOL). We were just grateful to get the boss jewel he dropped :)
I am possitive I saw Zaken on the list for who you can level the crystals on. However with the bugs and errors he is a pain to do go after baium he dies fast and easy. My allaince killed baium in 25 min and only one death a duo boxed SE that couldn't switch over and get the guy out of Baium's path in time.