Even better, Heat and Chill auras from multiple units stack. If you're sending a SC against Niefelheim or Abysia, he'll be immune, of course. But if you are fighting MA Man and see 15 Winter Wolves, you probably don't have cold immunity and probably don't even care. But then the wolves surround your SC, and each one's aura fatigues you, and suddenly you're getting something like 50 points of fatigue every turn you're fighting them.
I was quite surprised when I learned that.
