Typically used with Psyche.
In short: extrasensory perception. Put in terms of science, it represents a character's ability to observe objects, actions, or events removed in space or time — those phenomena which are just beyond normal cognition. Whenever someone says "I've got a bad feeling about this," it's the Clairvoyance skill at work. A talented clairvoyant could feel if a loved one is in trouble, the presence of supernatural forces, or the sudden violent death of a large number of people somewhere far away.
One Clairvoyance check takes no time, however a second attempt, trying to perceive something you did not previously, takes 3 AP.
By turning the knobs on your mental radio, you can tune into the emotional broadcasts from other beings at a distance. The signal strength is much stronger when the transmission originates from people you know, or when a great number of people are transmitting the same thing at once. From a vast distance you can see, hear, or feel when a sibling dies, an archenemy gains power, or an orphanage burns to cinders.
Roll a Clairvoyance check. The higher the result, the more accurate your interpretation. A roll of 5 means you're not close at all. A roll of 15 means you're pretty close. A roll of 30 means you've got it exactly, down to their location, outfit, and HP. Although, if the signal is weak (due to extreme distance) or you don't have much of a personal connection to the minds involved, the GM should offer up fewer details.
You can use Clairvoyance to glean information about the past or future. This manifests as a good or bad feeling about a course of action: whether it has already gone badly or will go badly. Retrocognition points your emotions toward the past and allows you to ascertain whether your friends across the country succeeded in their mission. Precognition directs your feelings to the future and reveals whether your plan of attack will fail horribly. The higher the result of your Clairvoyance check, the more detailed and specific your feelings on the matter. Anything under a roll of 15 is basically "reply hazy."
Divining the outcome of events can be done in your waking hours or through your dreams. The visions that invade your dreams are warnings of the future or important revelations about the past. The GM will ask you for a Clairvoyance check while your character sleeps. If you roll poorly, you won't even remember the dream. You'll be pelted with a sense of foreboding, but no clarity. "You feel like this man is familiar, but you can't remember from where," or "It feels like this tragedy has happened before. You feel like you should have known how to stop it, however, you didn't." Oooh, harsh.
Sensing the Supernatural
You can identify the presence of supernatural phenomenon just as easily as you can feel the warmth of a summer day. Clairvoyance is used to enact your mediumship and decipher the comings and goings of the spirit world. Use it to pinpoint haunted houses, reveal spirits' desires, and identify that a coma patient's astral body is elsewhere. The higher your result, the more accurate your interpretations.
A result of 15 confirms the presence (or absence) of spiritual activity. A result of 20 gets you some details (e.g. "what do they want?!"). A result of 25 gets you specifics (e.g. names and powers). A result of 30 is equivalent to sitting down to coffee with the spirits involved and hearing the whole story.