Metering for the ice. Spot meter on the subject. Since the lighting looks pretty even, you could have her stand still where she's going to do the trick so that you can get a spot meter on her face. Then make the manual settings to get the proper exposure. Then let her do the fancy stuff and you should be exposing correctly.
Canon 5Dc, Rebel T2i, Canon EF-S 10-22, Rokinon 35/1.4, Olympus OM Zuiko 24/2.8, 28/2, 35/2, 40/2, 50/1.4, 50/3.5 macro, 100/2.8, Canon EF 35/2, 40/2.8, 50/1.4, 85/1.8, Contax/Zeiss 135/2.8