Lore Influenced Game Mode
So I just recently got into the Lore of League, and I was surprised at how detailed it was. It's in depth enough to spawn a series of novels, and yet there's little to no emphasis on the lore, other than the tab in the champion info screen. I think it'd be an extremely productive idea to start a lore influenced game mode, a "campaign" or "story mode" of sorts.
The way I envision this would be something similar to a regular game, except with the champion pool based on the lore, and possibly an open arena style map (or at least something slightly different from the rift.) For example, a Demacia vs. Noxus fight, with each of the champions, or just a pre-generated team, from the respective city-states available free-to-play, would lead to not only a more widely accepted appreciation of the lore, but also would give players a chance to try new champions in ways other than ARAM or the weekly free-to-play (possibly offering champion mastery but no XP or something similar. If the teams were pre-generated, it'd be cool to see some of the partnerships come to fruition on the rift, such as pre-teaming
with
, or
with
, or
with
. Or even
against 
This is the best way I can envision expanding the lore and making it more known to players, short of novels of Legends. Which now that I mention it, would be even cooler.
TL;DR: Make a lore based game mode that isn't filled with cinematic scenes.