The Shaper of Thoughts says...
No one knew where Sar'ai was. The last anyone saw of her, she was meditating in one of the rooms offered by the fort. When inquired, guard said he thought he saw the half-drow leave the fort shortly before the alarm bells began ringing throughout the town, but he didn't think to ask to where she was headed.
The wizard stood and could only wait as from her view she saw the large half-dragon bark out as apparently he saw someone that was either out of her view or perhaps invisible. Then the voice of the monk Cratol echoed from the gates accepting who could only be Cyanwrath's challenge.
Sar'ai felt as if her stomach dropped, but she had to keep her calm and wait for the perfect time. For at the moment she was surrounded by the growling war-chants of dozens of kobolds. Her expression though remained stoic as she was getting her ques from the humans in the large force, each appearing to be a leader of smaller groups of kobolds to give the little dragon-kin some structure to their ranks. Out of Character:
so, unless it would have been impossible to so, in which case just assume Sar'ai is up at one of the towers, she cast disguise self to make herself appear like one of the humans in the attacking force and has taken up a spot on the outside of the wall amidst the enemy. The way I figured this could work is that when Elanna returned, she gave a description of the individuals she encountered and come the early morning, Elanna was keeping a watch and saw the force coming in time for Sar'ai to sneak out and just kind of blend in as the thick fog obscured some vision from the kobolds, and if she looked like one of the humans who they were used to seeing, then they probably wouldn't think to question her.
Her plan is to catch a lot of the kobolds by surprise when they are given the orders to attack and then one of "Them" immediately starts attacking them from within their ranks, hopefully causing enough confusion to impede their progress slightly. Now, Sar'ai is not suicidal and believes she can cause enough disruption and then get out before dying. I guess we'll see how well that works out.
Again, if this would have been not something Sar'ai could have done in time, that's fine. Edited: Brandonfett on 16 Hours Ago