So which keystone is going to get nerfed next?

My guess is strength of ages cause it's used by junglers. Then maybe another thunderlords nerf with another stormraiders buff to try and prove this keystone system isn't just a poorly thought out mess and knowing Riot's work schedule we should be well into 2017 where they announce another mastery rework and we get to do all of this again (this time every mastery tree only has 1 mastery cause having too many masteries is toxic).