From Ardrana

The empathy spell allows the caster to sense the basic needs, drives, and/or emotions of any unshielded mind. The spell gives no result for creatures protected against detection, psionic creatures, or emotionless creatures.

The reverse of the spell, mask emotion, conceals the emotions of the protected creature for ten minutes.

Note: This item originally appeared in this form in Polyhedron Magazine #22 by TSR. Their inclusion here is for the purposes of providing context for the campaign only.