LoL Friends is an IM app developed by Riot Games to let you stay in touch with all your League of Legends friends and buddies anytime, any place.
The app works just like any other chat app, only here you'll have all your friends from LoL. In addition, all messages sent using this app will sync with your account, meaning you can start a conversation on your Android and continue it on a PC.
LoL Friends is a messaging app aimed at a very specific audience (LoL players), whose limited options consist basically of chatting and adding friends.