Runeterra and canon

This shit was conceived as a roleplaying environment in which members can weave stories and explore the expansive world that Riot has provided us in the lore of League of Legends. To do so, we need to be able to dissociate ourselves from the lore that defines the game.  We recognize that in this time, Riot has continued to expand upon, modify, and incorporate new information into its own canon lore. While we welcome the introduction of vibrant new characters and themes, the continuity of events in our world do not always allow us to incorporate these modifications fully. Please keep the following considerations in mind when planning your stories.

TL;DR
Almost anything goes, but the only shit you HAVE to go with is that summoners and the IoW canon is the prime world.