I would have suggested the shields first, but it depends on his activities. If he plans on learning to tank Nex, if he plans on moving on to Vorago afterward, etc. With 250M you could get virtus, a wand (even if treachery), and have the farseer to tank at Nex and Vorago. IDK, I've never used defensive abilities or tanked before Vorago, and now that I've realized how much you can abuse resonance, rejuvenation, immortality, and the others... It's sooo much fun.