"I'm a man of many talents," Strange responds, with a wry little smile. Seeing Susan has lightened his mood considerably. Where Strange had been glaring at and working with the magic to an extent that he wasn't paying attention to anything else, when he hears Susan's voice and turns to look at the kid, Strange gives him a small smile.

"Something odd happened with my magic in the Athenaeum. I want to make certain it still works properly."

With a gesture of his hand, one of the large spikes of earth starts to vanish in the ground. And then, wry smile still on his face, Strange nods at Susan's feet. The ground beneath Susan rumbles slightly: it might be enough to knock him on his ass, but it's certainly not a large enough rumble to cause any sort of major damage. This is just him playing around and being a dick.