It looks a bit like the tree in Halure blooming, in fact: radiating out from Estelle, the flesh and acid around her will ripple like it's reacting to her power. Any bit of flesh or wall-over-flesh her power touches will start to distort, bulge, and then suddenly swell up, bursting through the cement into weird meat bulges. The cistern will heave around her, splashing acid everywhere. All this attention will draw those flesh bugs, which will swarm to try and get rid of her.