I strongly suggest you DON'T go for this build, as Maxing wings out before maxing out anything else is completely wrong and waste of AP.
Better build would be (Late Invisi Shot)
Invisible Shot 3 ->Gun Mastery 15 -> Gun Booster 5 -> Gun Mastery MAX -> Invisible Shot 10 -> Fake Shot 5 -> Invisible Shot MAX -> Wings 10 -> Fake Shot MAX -> MAX Booster or + Grenade