It’s — my magic isn’t so rigid, [ relenting, ] though I appreciate your interest in the technicalities. The weave that composes it is all around us, you see, so I need only to thread it thusly. [ an accompanying gesture, free hand threading the needle. ] To use another spell as an example, I could direct a fireball your way and make it so you did not feel the lick of a single flame.

[ as for the aforementioned technicalities, he waves a hand. ]

It can be otherwise tailored, of course. To allow specific individuals, respond to a code-phrase, punish offenders. If you can imagine it, it can be done.