Ace
The Vistani is not totally uncomfortable in the Shadowfell; after all, the plane is the home plane of his wandering people. His heritage does not, however, give him any sort of adjustment for the smell.

Endurance: (1d20+4)[20]

Spoiler
Show
At least in the core 4e setting, the Vistani are actually from the Shadowfell, though their caravans can cross planes back and forth readily. It is possible that, given that, Ace has even been to the Plane of Shadow before, though obviously not this part of it.