Ironthunder Horn

(Spell Compendium, page 126, DnD 3.5)

Transmutation[Sonic]

Level: ; Bard 1; Sorcerer/Wizard 2
Components: V, S
Casting Time: 1 standard action
Range: 30 ft.
Area: Cone-shaped burst
Duration: Instantaneous
Saving Throw: Reflex negates
Spell Resistance: Yes

The last words of your spell boom out with a thundering roar, knocking the foes in your path off their feet.

You create a deep resonant vibration that can shake creatures off their feet. Creatures in the area must succeed on a Reflex saving throw or fall prone.