Co-op campaign with monthly (or so) realised chapters
I think a campaign mode for LoL as monthly event would be very fun, it could be endorsed with drops and the likes (with the new crafting system it can be easier). I like to wonder about using the champions of this game in an hack'n'slash kinda world, where i could experience the lore more directly and use their abilities in a totally different context. It would be also fun to meet the characters as npc and see what they look like outside the league. One of the great memories i have of the special modes of this game is the Doombot of doom Mode, because I like co-op and i think it's a nice thing to do when you feel like playing with your friends but you don't want to be competitive , but i also want to explore Runeterra in the best way i can imagine: through the game. (Sorry for the bad english.)