By use of this spell, a caster was not only able to detect the presence of sentient creatures, but also their exact location. The spell was able to function even through walls or other solid material. A caster was able to distinguish separate minds in a group, and if a spell or magical item was used by the targets while this spell was in effect, the caster was able to know the exact nature of the magic used including words of activation. The spell was not able to detect a creature whose thoughts were warded by magical or psionic means. Phaerimms used this spell to detect the presence of hidden creatures and were immune to its effects if it was cast upon them. A caster was unable to cast this spell near or within a mythal.