currently in internal testing:

3 Stacks - Rengar gains 15% movement speed while in brush(bonus does not persist outside of brush like Nidalee's)
6 Stacks - Rengar gains 100 range on his Leap(slightly nerfed due to having access to it earlier.)
9 Stacks - Rengar retains movement speed from his Ultimate for 5 seconds after exiting his ultimate. (Rocket cat goes zooooooooom)



(Rocket cat goes zooooooooom)
^Oh riot cat_lol