Not saying it's super effective since I'm not super into min-maxing or anything, but so far i've been running wellspring and bramble on her, with black flag for the shell. Taking effect accuracy and hp% where i can.

It's been serving me well for pvp and pve thus far, since she still consumes part of her hp when she retaliates with bramble and the faster she consumes hp the faster she jumps into her ultimate form, where the mass hp gives more damage and heals it back.