After Phoebe kicks Lord Dyson, she falls to the floor as he goes to kill her with an energy ball. Phoebe looks up and remains frozen. Phoebe wouldn't be stunned and just stay there, she has faced worser moments then that before, and would at least kick him. Secondly, Piper turns to Phoebe and Dyson and she's startled by what she sees and raises her hands. A few seconds later after Piper did that Dyson shimmers out. He should of froze.