Garrison Campaign: In the Shadows

I need your help. Iskar has gone missing. I have reason to believe he has followed the remnants of the Sethekk who have been gathering here in Tanaan. I've been investigating and... what was that? <Reshad's voice drops to a whisper> There is movement in the shadows, we are being watched! Take these vials, they form a gas with a terrible smell when the liquid comes in contact with the air. Smells terrible, they won't be able to resist it. Use them to drive our watchers out of hiding.