The way I look at it you'd be working around the current lore and not actually be worrying so much about the summoner's rift and the league itself except when the rune mages use it to decide conflicts( Which is really the whole point of the "League of Legends". Where the super powerful rune mages stop massive conflicts and force them to fight one another to decide the victor.) I don't know think it would be a good idea to use the current characters though. I personally don't like making RPs off of stuff that is already made. Now that I remember I'm pretty sure they call it the Institute of War.