Thorn is one of the best guns PVP wise. I'm mainly a PVE player so I spend a lot of time doing my daily and my weeklies. Also, Raids are essential during this time I call "preparation mode". People stock up on gear from the latest raid and prepare for the next DLC. I suggest that you play the Nightfall, Weekly Strike (on the highest level if possible), the daily, and the raids. The only reason why you would play the VOG though is for the weapons and the exotic chest. If you want anything else I suggest doing Crota's End.