I normally play aram now, but sometimes i do a rift to get an S token. People say you have to get a S treasure chest from a new champion, but how do I know which champions have an S already? Is there some way to find out?
If you go to your profile and look at champ icons, the ones you've got a chest with have a gold boarder around them.
Also if you hover over a champ icon it will tell you the highest ranking you've gotten with that champion/total points/mastery level and all that.
Go to your profile, go to champs, and when you hover over them it will tell you your season best grade for that champ.
