How the heck do I kill Doppleganger?

I'm a Level 19 Monk / Elementalist and have been going at Dopple for the past hour and a half! I've been using every tactic, skill and trick I know to kill him, and still I can't get him to half health!

Can anyone give me some tips or suggest a skill / Skill line to use?

~Veripare

Bring useless skills to beat him. Put up attunements from your ele side, and he'll use them. Whatevers useless, bring it. He'll be wasting time using those, while you're hurting him.

Thank you!

~Veripare

Also, pack Healing Breeze as your only source of healing, the Doppleganger won't use it

At the time I fought Dopple as my Monk, I didn' tknow about Healing Breeze, I just went all out with Smiting and Necro sacrifice skills. In the end we killed eachother >,> lol