I'll add in Dark for a primary. Why? You get to add in control. You also add in def for all and +res to psy which is Inv's biggest weakness. While Inv has a Dull Pain type of power, Twilight Grasp can fill in nicely if they need extra help. Secondary can be up for grabs pending on if you duo a lot by yourselves or not. If you go lower mob count, then something more single target focused is fine. If you want to join teams, going a bit more AoE is fine. /rad and /beam are some of the few secondaries I would look at as IOs/procs make them a bit more interesting in today's game.
My only complaint is them going Energy which a bottom feeder for melee damage although fixes are on their way. Depending on when you stopped, Savage might be worth a look. I personally rolled a Savage/rad, but haven't officially kicked the tires on the build yet. It works in my head though base on previous characters,