(Well, to maintain the RP according to what Otebon would know as opposed to what is in parenthetical statements and I, as the poster would know...)
*Looks up to see what is bound within the circle.
"That's strange... unless..."
*Immediately stands and runs away from the circle.
"Please don't say he carved Xercali. Please don't say he carved Xercali. Please don't say he carved Xercali..."
*Otebon's mind ran along what may have happened.
The only runes in the circle were ones of binding. Nothing major, just to hold whatever was in the circle. If he wrote Xercali, that's an open invite to the Outer Planes. The flash wasn't black however, so the probability of that is small unless he wrote it in the fourth quadrant under the Yeteria rune. The circle was a binding circle. What could he have done? Bound light to make himself invisible? If so, it'll only work inside the circle. I didn't write any permanency runes...