Master Glox (Grandmaster Glox's sparring form) is an Iksar monk mob that drops a Mark used in the Shackle of Tynnonium quest. He drops the Mark (one of three) and a potion that looks different than this but has the same effect. Both port to the same spot in Field of Bone, both have a 30 second cast time. A relatively free way to get this potion (though not exactly honest) is, if an Iksar, accept Grandmaster Glox's challenge to spar, kill his level 40 form, loot the potion, and camp repeatly in front of the door until you log in on the other side.
-By the way, the Shackle of Tynnonium achieved by Glox's Mark and two others IS a part of the Whistling Fists quest, as others have said-
Orestes Peacebringer
Monk of Terris-Thule