For a long pause, she draws her hand back to herself, placing it on her chin as she thinks over his explanation. When she thinks about it logically - yes, that makes sense. Even the existing supernatural abilities in her world require rules and range, have conditions to clear. So it makes sense that certain kinds of magic rely on something spatial.

The other part of it — the will part — that's a bit more abstract to her.

"Force my will onto theirs? It feels like I'm trying to do that already, though."

She doesn't sound discouraged— just mystified, while she tenses her brow, focuses a bit more in attempt to continue her spell. For a few moments, she tries darting her eyes around to different parts of their body, as if that'll help, before locking eyes for a brief moment with their "example," which results in incremental growth of the stone encasing his midsection.

Obviously, their eyes dart away as soon as possible, halting the effect.

"Oh! Did you see that?"