(Player's Handbook II)

Illusion (Phantasm) [Fear, Mind-Affecting]
Level: Bard 2, Beguiler 2, Sorcerer 2, Wizard 2,
Components: V, S,
Casting Time: 1 standard action
Range: Close (25 ft. + 5 ft./2 levels)
Target: One living creature
Duration: 1 round/level (D)
Saving Throw: Will disbelief
Spell Resistance: No

You cripple a target with sensations of falling.
The subject of this spell becomes dizzy as the ground seems to drop away beneath its feet.
The subject must succeed on a DC 10 Balance check at the start of each turn to take a move action.
If it fails, it cannot move.
If it fails the check by 5 or more, it falls prone.
While affected, the subject also takes a -2 penalty on attack rolls and saving throws.
Airborne creatures receive a +4 bonus on saves against this spell and do not need to make the Balance checks.