Riot recently released a short story called "The Bird And The Branch", heralding the arrival of a new Champion called Taliyah — a stone mage from Shurima who falls under the guidance of Ionian Champion Yasuo. While her abilities and splash have yet to be revealed, the story shows that Taliyah already fits into League's once-neglected lore better than a number of recent Champions have.
Taliyah is a young female stone mage from the desert nation of Shurimah — one of the first human characters to be introduced from that region since Sivir. Her abilities seem to constitute something like the Avatar universe's Earthbending, though how that will turn out in the MOBA's gameplay still has yet to be seen. Taliyah's gameplay designer has been confirmed to be Daniel "ZenonTheStoic" Klein, who was also behind Tahm Kench, Lucian, and Azir.
"The Bird And The Branch" can be read here, though there are a few important points if you don't have time to read it all yourself. Taliyah doesn't seem to have a strong alliance, but the story has her on the run from the Noxian army. Yasuo takes her under his wing to train her, though they part ways at the end of the story with Yasuo sending her to the Freljord. Interestingly enough, Taliyah's story has her providing the thread which Yasuo uses to tie back his distinctive bushy hair.
While in Ionia, Taliyah hears rumors of a bird-god returning to Shurima (ie, her fellow League Champion, Azir) to enslave its residents, and she sets off to try and protect her family. Whether this will factor into the game's lore or another plot event later on we can only guess at, but it's nice to see League putting effort into giving its characters interconnectivity with the world and its lore again.