Proviron is a great compound, one of my favorites actually, but I would not expect anything serious from it. In terms of muscle building it will not help at all. It will boost libido, and will increase free testosterone levels, but not really much more than that. Maybe it will also have some hardening effect. Your best bet would be a stack of Cardarine GW and Ostarine – they will boost your performance and will help with muscle building without any side effects to be concerned about. All you will need later, is a nice natural testosterone booster after the cycle.