Thunderstomp

You stomp your foot or strike your weapon against the ground or floor, creating a ripple of power that you can use to trip a creature. Attempt the combat maneuver check to trip the target, but instead of your base attack bonus you can use your caster level, and instead of your Strength modifier you can use your spellcasting ability score modifier (Intelligence for magi and wizards; Wisdom for druids and rangers; Charisma for bloodragers and sorcerers). This does not provoke an attack of opportunity. This spell has no effect if you cannot reach the ground or floor, or if your target is not in contact with the ground or floor.