Hello,
Just got an S- with Jhin on poro king mode but didn't receive a chest. I thought you got chest with S- or more in every mode now? Is this correct?
http://www.lolking.net/summoner/euw/24690178/Mrouu#matches
Thanks in advance
Just checking that you are aware that you can only get one chest per season on each champ, so if you already got a chest on whatever champ you were playing that could explain it. (You can see a border around the champs you've already earned chests with this season on the Collection screen).
You should be able to earn mastery points and chests in Rotating Game Modes, afaik.
