As far as I know she's pretty important to the place's lore Thousands year old alpha predator that's practically mythology at this point. I woulda thought she'd be on the site with all the other Shurima peeps but I guess not :/
This response from Jellbug in the recent Shurima Story Q&A might just answer your question:
While Rek'Sai does burrow through the Shuriman desert, her identity is inexorably tied to the Void. We're definitely looking into telling her story in the future.
She's not considered from Shurima, she's Voidborn and belongs with the rest of the Voidborn.
reksai is clearly a void champion
