As someone who loves card games, this has long been my favourite. It's quite a unique format compared with magic and hearthstone, and surprisingly well balanced every patch. Super free to play friendly, too. I have only spent money on cosmetics because I really like the business model. The app is well-made, yet to encounter a bug other than some connectivity issues which could be down to bad WiFi. A real win from Riot on this one - definitely give it a go.