The Empress OF the Elements, Qiyana,
From the looks of the Trailer, it looks like she's in the Kumungu Jungle which is where Zyra From the base on her Lore. I have a feeling Zyra and Qiyana have some connection to each other or Possible Interactions with each other. besides, That's probably where the New Nations is going to Raise up. They have probably been hidden in the Jungle for the Longest time and though it's time for their Champion to Join the Summoner's Rift.
I also Think she'll have some interaction with Rengar, Nidalee, Teemo, Ezreal, Kha'zix, Ivern and finally Neeko.