UPDATE. I tried Halls of Lightning tonight. Not even a single death in there.

First, here was my 2nd drake run: (6 minutes left)


Bjarngrim with buff for achievement:


Volkhan with achievement:


Ionar: (this was the one boss I was really worried about) The sparks were extremely easy to heal through, so I won't need any elementals next time:


And the final boss. (I popped bloodlust before pulling him and took a few seconds to hit screenshot as you can see the achievements fading away), which means he was dead in about 30 seconds.