I was running Arx with some friends yesterday as it was the normal pledge (V12 instance), and we had some trouble with the snake boss (Fanged Menace).
Whenever he went into his healing/poison mode, there was no way to interrupt him and he would heal all the way back up. We had a standard, a veil and a nova on him at one point and he still healed back up.
Now, I've run this dungeon before at different levels, including tanking it on a level 22 when it was set to level 29, and a lower vet instance a week or so ago and that boss never struck me as problematic.
Is this a DPS vs Heals race? I would expect to be able to interrupt a self healing boss (like you can with other bosses who heal themselves).
Is it bugged or were we doing something wrong?