Argent manors spell weaver boss

Hey guys, just a question about the final boss in argent manor, spellweaver. Has anyone been able to successfully kill this guy or at least encounter his 2nd form. My group does fine on his first form, but around 40% hp, he freezes the group and runs through a portal in the back wall. We try to follow him and click the portal, but nothing happens..we don't know how to access the room with his 2nd form. We've been able to kill all bosses in both elements and argent, except this guy, any help would be greatly appreciated. P.s. on a side note has anyone been able to loot primal spirit cloth gloves from the gate's treasure chest...this is probably the only piece out of all sets I have yet to see....so I think that chest is bugged.Thanks

 

just Try to log out if you are in the last boss