Elemental Susceptibility shouldn't be a free skill. This has probably been brought up before but just giving damage on a free cast without any pre-requisite isn't very balanced. I'm not sure how it's gone unchecked this long but it's pretty glaring.
I mean, Elemental Susceptibility doesn’t do that much damage on its own, and the status effects it causes don’t last that long. Vateshran is an issue, but that’s about the gear and not the ability. And it’s not like adding a cost to it will stop people from using it, anyway. There are far worse things for ZOS to look at than this.