Traitor

This ability is passive, and functions even if the skill user is left on the Icarus (lacking a working spacesuit on a planet without oxygen).

Combines well with to help survive the misfortune you cause. Otherwise, "accidentally" bringing a broken spacesuit is less suspicious than "forgetting" one, though both ought to be noted, especially if the expedition goes unusually badly.

Beware of Forests, Insects and especially Swamps, where negative events cause illness, which help to identify humans - or Mush.

The best use of this skill is definitely during desperate O2 supply runs, when the crew is forced to take bigger risks just to prevent asphyxiation. - Either to make sure those risky zones hit home, or to make the O2 pump itself fail (20% chance of no with a Traitor on board).