The telepathic warning is a great idea, I think. Do we want to cast sleep? Possibly take out one or two of the guards, but also possibly the Knight Captain. If there's something Carradoc can do, let me know.
OK, just to confirm what we're doing...
Thaliss is going to psychically clue the Knight-Captain that we're about to rescue him. Damien goes in there and try to Fletch his way close enough to the Knight-Captain and convince them to let him just take the dude. If that doesn't work, he casts Darkness on himself and tries to grab him?
I remember we saw their symbol in the temple where we fought Qorbo. So, I guess Damien is going to throw up a triangle in whatever orientation they use. Thumbs and forefingers, fools!