Hover is a built-in state. When an object has a Hover state, it will automatically show when the user mouses over the object.
A trigger can only perform one action. (That is unless it has one or more conditions along with an "Else" statement.)
Based on your description, it sounds like you have a hotspot placed over an object so that the hotspot can be clicked to show a layer. That's not needed. You can add a "when user clicks__" trigger to any object. Here's more info: https://community.articulate.com/series/articulate-storyline-360/articles/articulate-storyline-360-user-guide-how-to-work-with-triggers