Can't beat Diablo

I’m a Lvl 32 sort of Bowazon with a few skill point assignment errors. I can clear the Chaos Sanctuary but can’t beat Diablo. What is the best merc to have? Also, should I redo earlier ActIV areas to get to Lvl 33 and thus better gear? Thanks.

You will want to be using guided arrow with a decent bow for your level. What level guided arrow do you have and what is your bow like? What do your stat point allocations look like?

Thanks for your suggestions…I succumbed in the end and got help killing Diablo.