Keltham will Prestidigitate his god's symbol and a question mark, in diffraction-grating iridescence that somebody who wasn't deeply involved in the Project might not understand the optics of well enough to cast an illusion faking it, and also he's going to weave in some small Baseline fancy script that's going to look like a lot of indistinguishable Elvish curlicues to anybody who doesn't read Baseline, but which Keltham himself can immediately check for coherence.

"How are we staying in contact once you've Teleported?  Telepathic Bond, or does Message work across Greater Scry?"

Keltham is trying to avoid thinking about how much it costs Conspiracy to claim that he needs to give all his instructions in advance (20 bits).

Keltham will Prestidigitate his god's symbol and a question mark, in diffraction-grating iridescence that somebody who wasn't deeply involved in the Project might not understand the optics of well enough to cast an illusion faking it, and also he's going to weave in some small Baseline fancy script that's going to look like a lot of indistinguishable Elvish curlicues to anybody who doesn't read Baseline, but which Keltham himself can immediately check for coherence.  That hopefully makes it complicated to change on their end and fake in an illusion on his end.

"How are we staying in contact once you've Teleported?  Telepathic Bond, or does Message work across Greater Scry?"

Keltham is trying to avoid thinking about how much it costs Conspiracy to claim that he needs to give all his instructions in advance (20 bits).