Tremorsense

(Underdark, DnD 3.5)

Transmutation

Level: ; Harper Scout 3; Ranger 3; Sorcerer/Wizard 3
Components: V, S
Casting Time: 1 standard action
Range: Personal
Target: You
Duration: 10 minutes/level (D)
Saving Throw: Will negates (harmless)
Spell Resistance: Yes (harmless)

You can automatically pinpoint the location of any object or creature within 30 feet that is in contact with the ground.
Arcane Focus: A fleck of skin from a creature that has
tremorsense.