The cloud doesnt have much of a smell. It looks like fog until it’s on you and then it’s two late. A couple of sucking breaths and your chest is one fire and your eyes are bleeding. Terrible stuff, but if you think it is tough on the living, you should see what it does to the dead
PVT Thomas Quinn.
A casual remark by one of the party about something met on a previous adventure leads to a summons to and grilling by the Mages' Guild (or equivalent), probably resulting in an expedition back to that area to recover the things for 'study' by the Guild. The party's presence will be 'requested' for this expedition.