It can play LoL without even trying it is not a demanding at all. The integrated Intel HD 530 graphics core in the quad core i5-6300HQ can run the game at 1080p with max graphic settings without any problems. You don't even need to use the GTX 960m.
Below is a link to a video demonstrating LoL running on an Asus laptop with a dual core i5-6200u and the Intel HD 520 (less powerful than the HD 530) at over 70 FPS. Since the LCD screen operates at 60Hz (like the Dell), at most only 60 FPS is displayed.
https
/www.youtube.com/watch?v=IZ9ZCxs1iuc&t=43s