Clairaudience/clairvoyance

Clairvoyance, sometimes known as Clairaudience/clairvoyance, was a divination spell that allowed the caster to put an invisible magical ear or eye in a well known place, and then hear or see what the magical organ detects from far away.

Effects
The caster had to choose an aural or visual sensor at the time of casting and choose a place in which to put it. The range of this spell was at least 600 ft (183 m) and increased with the level of the caster. The location had to be either obvious or well known to the caster, and had to be on the same plane of existence. The eye or ear could not penetrate magical darkness or silence, but the eye could see in a 10 ft (3 m) radius in natural darkness. The caster could not move the sensor once it was placed, but the visual field could be rotated as desired. The scrying lasted one minute per level of the caster.

If perceived with something like true sight the sensor would have looked like a intangible, luminous orb about the size of the casters fist.

Components
In addition to verbal and somatic components, a focus or holy symbol was needed as well as a small horn for the aural sensor or a glass eye for the visual sensor. The later version of the spell needed a focus worth at least 100 gold pieces and a jeweled horn for the hearing version or a glass eye for seeing version of the spell.

History
the spell was attributed to Netherese arcanist Zahn. Its hearing and visual aspects were originally developed separately. The sound sensor was developed first, in -928 DR, with the name Zahn's hearing, while the visual sensor was developed only in -926 DR with the name Zahn's vision.

After the Second Sundering the spell became simply known as claivoyance, while still retaining the ability of switching between visual and sound sensors in a single casting.