His pain is every bit as satisfying as she anticipated--as is the fact that she's made him retreat, even just two steps. It's a much-needed reminder that he isn't as all-powerful as he'd have her believe.

Rey rips her staff away from him viciously and raises it to take a brutal swing at his injured side. She'd rather hit him in his stupid face, but with that horrible mask on that's sadly not an option. But then his hand comes up--and she realizes she can feel him calling on his power this time, having experienced it a handful of times--and her staff stops infuriatingly short of its target. Rey struggles, fights his invisible grip as hard as she can, but her arms only twitch.

Her voice is as frozen as her body, so her frustrated scream has no outlet but through the amulet... and directly into Kylo Ren's head.