What's the problem with Gloams?

[JustAGuy]

Vengeance should easily solve that, since you get +elemental damage to it from Salvation, which I personally max anyway to get +dam to Holy Shock. With Vengeance on, switch to Resist Lightning and your merc should be able to tank them naked

Good call. I used to use Resist Lightning all the time, but ever since I got 95% lightning resist and lightning absorb, it never occurred to me since to use it. But yeah, that would easily do the trick.