It is OP in some situations but there are ways to beat it or at least slow it down. You have to sort of aim. Vertical dodging can be very effective. Getting behind can make a stormcaller waste time trying to get a clear view of you. There is little or no boost to armor, a shotgun can end the super fast. I mainly play as a stormcaller, and the situations I live for as regards using the super are situations where several opponents are clustered in a small area, eg relic or camping a heavy box, in a room with a ceiling that prevents a bunch of multilevel chasing. In that scenario, yes it is crazy OP.