Lucidity

Typically used with Psyche.

In short: dis illusions. While Clairvoyance is about seeing or feeling things on a supernatural level, Lucidity is about seeing through things which do not exist at all: illusions. Phenomena that affect the five senses in an magical way may require a Lucidity check to determine if the character will experience things as they actually are and not as they were altered to be.

Resisting Spells

Many illusory spells can be defeated with a Lucidity check, for instance Diversion and Shadow Puppet. In this case, you may add any points in Magic Defense to this roll. The mage makes a Casting Roll. You make a Lucidity check. If your result meets or exceeds the Casting Roll, you elude the effects of the spell.

Note that you must first be aware of the illusion in order to see beyond it. If there's an illusory dog bark that you doesn't hear in the first place, there's no grounds for disproving it.