Thrasher Rei'Sai Skin Concept
https://www.youtube.com/watch?v=RZihiggKjtk
I can picture it. Rei'Sai with more wormy body, crawls more than her normal model while half-submerged. More dusty effect when she moves underground due to earth shifting. Green corrosive spits for her burrowed q. When she burrows, she doesn't dive, she pulls back into the ground with her wormy body like Thresher Maw.