She decides to keep experimenting with it.

Before Constance could respond to Yuri's question, she saw how her skin was becoming visible again, and shortly thereafter, she was now as normal as before she casted the spell. Meaning that Potency wasn't the only flaw that her so called master spell had.

"'sigh', i guess we could do some tests with the spell", Constance said a bit disapointed by the constant shortcomings of her spell.

"Well then, i guess we should see if casting the spell again we could do it right this time", Yuri commented, upon which he and her, returned to the lab to do some tests, but not before she had the chance to rest a little.

And so, after a quick nap, Constance made the effort to cast the spell right this time, however, despite her newfound concentration and awareness, the spell failed yet again, for as soon as the smoke cleared, her clothes were still visible while her skin not.

Not wanting to quit, Constance then took it for himself to repeat the spell, only to fail another time, upon which she did it again, with even more concentration this time, only to fail again regardless, and so on, and so on, until at last, both her and Yuri were tired from the effort.

"Goddammit!, why it never works every time!!", the still semi-invisible Constance yelled angry. "All that i want is to just go able to go back to Fódlan undetected.", she added.

Not liking to seeing her friend in distress, Yuri the began to think on a way to help her reach her goal. He knew that just continuing trying with the same spell again would only result in more failure, and that he needed to find a way to make use of her current spell, despite how incomplete it was. So how ?, how ?