Originally posted by ElOhTeeBee:

I can't consistently beat him - he puts out a ton of damage AND inflicts pierce AND he has a ton of HP AND a ton of defense when magic damage is unreliable without truestrike.

Have at least 2 shields (cuz he usually stops after 2 consecutive use of his skills), or just straight up build Freeze because his skill is phys damage. Aiming for magic gems if you see him on the map as the first boss, and you can change it out after going to the next boss.

Edit: I recommend bring at least one bomb gem to clear out the mobs, only need 1 to clear the map out and leave the boss exposed.