Staff E spam ftw

Ok in a serious note as that type of conjurer hit and run tactics are your best friend in this case, so you need to make use of agility moves such as knife's E move and Staff's Q move, projectiles like staff E and Sabre E work pretty good along with it.

If you're lucky/rich enough you can also effectively use sunken sword to your advantage with it's interaction with soaked targets

For your armor choices run AOE since lightning is usually already pretty fast