I hope you're not too attached to the lore behind League of Legends , because it's about to be chucked out and replaced with something new. As the rest of LoL has changed over the years, Riot Games say that the original lore has held them back, leading to "creative stagnation, limiting the ways that champions, factions and Runeterra itself could grow and change". So the lore's being updated to give Riot more freedom, allowing them to tell (hopefully) more interesting stories, and to give their characters better justifications for battering each other across a series of lanes.
The full details are here in a massive blog post by Tommy Gnox and LoL's narrative team, but I'll quote the relevant parts explaining why LoL's previous backstory is is being altered to allow Runetarra to be "a world in which the factions and champions we all know and love have full freedom to grow, travel, and kick ass on a worldwide scale."
"In the early days of League," Riot say, "we created a fictional background that would justify how players could control champions during games. We came up with concepts like Summoners, Fields of Justice, an Institute of War, and indeed, the League of Legends itself – all in an attempt to provide fictional context for in-game action.
"After a while, these early choices began to create unexpected problems. Every new champion needed a reason to join and remain in the League, and as their number grew, the net result was that over time the world started to feel, well, small, and eventually less interesting. The institutions we'd designed fostered creative stagnation, limiting the ways that champions, factions and Runeterra itself could grow and change. Furthermore, the very idea of all-powerful Summoners made Champions little more than puppets manipulated by godlike powers. The background we'd created to explain in-game action was ultimately restricting the potential narrative development of the game's defining characters."
To pick up that earlier point, here's how Riot hope to achieve this: "from champion interactions to bios to events (and beyond), we aim to expand the scope of League's story and pursue a more dynamic and wide-ranging world fit for the outsized capabilities and personalities of our champions".
If you've grown attached to the original backstory, Riot assure fans that "League's original lore remains a cherished part of its history".
In other recent LoL news, Riot talked depth and player engagement at PAX.