Rek'Sai could stand to have an actual passive
"Her W heals her" isn't exactly a gamechanging component of her kit and could jsut be written out on the W itself.
Meanwhile, she lost her R's passive AS when it got reworked. Why not have an AS steroid for the passive?
Fury of the Xer'Sai (Passive) Removed: While burrowed, Rek'Sai consumes fury to recover up to 20-190 health over 3 seconds or until she reaches max health NEW!: Damaging enemies with abilities grants a stack of Voidrage, up to a maximum of 3 stacks. Basic attacks consume a stack of Voidrage granting 5/ 7.5 /10 / 12.5 / 15 / 20 / 22.5 / 25 / 27.5 / 30 / 35 / 40 / 45 / 50 / 55 / 60% bonus attack speed for that attack at levels 1/2/3/4/5/6/7/8/9/10/11/12/13/14/15/16.
W (Burrow) NEW! ?: While burrowed, Rek'Sai consumes fury to recover up to 20-190 health over 3 seconds or until she reaches max health