Tremorsense

(Spell Compendium, page 224, DnD 3.5)

Transmutation

Level: ; Ranger 2; Sorcerer/Wizard 3
Components: V, S
Casting Time: 1 standard action
Range: Personal
Target: You
Duration: 10 minutes/level (D)

You cast this spell and know where each of your opponents stands. Their presence is marked in your mind like ripples radiating along the surface of a pond.

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.