I drop two earth elementals, then move back a bit as Vex closes in. I use CL whenever ready. That way the adds are (indirectly) taken care of; I never take Vex out of target during this fight, and the adds do stick to the elementals, usually.

My strategy is simple: as much damage as fast as possible.
So (for damage) I got 5 x wrath, 1 x wrath of air, EM, trinkets and bloodlust activated when I start this fight. When Vex comes my way I may drop novas while moving backwards and set wrath back up when they've gone off.

It's more of a brute force approach than fine arts, but it works for me.
Hope this helps.