LoL is fun, if he enjoys it let him do it, noone is getting hurt by it and its a pretty good game once you get into it. DOTA is also a good game, not saying anything about it, and since you can play LOL entirely for free (only advantage to paying is looking cool) it is a nice way to hang out with friends. I play LoL with my RL friends, my GF, my brother and such, and once you manage to reduce the toxicity (people play the Blame Flame Game too much in it, but you must remind them: Its a game, were friends, why you are yelling at each other) its a nice way to spend time.