Inaccurate?

Trip Vine

(Heroes of Battle)

Transmutation
Level: Druid 2, Ranger 2,
Components: V, S, DF,
Casting Time: 1 standard action
Range: Medium (100 ft. + 10 ft./level)
Area: One 10-ft. square/level (S)
Duration: 1 hour/level
Saving Throw: Reflex negates; see text
Spell Resistance: No

Trip vine causes plants within the area to grow together to form a tangle.
Any creature entering an affected square must succeed on a Reflex save or fall prone.
Any creature charging into an affected square takes a -2 penalty on its saving throw.
If this spell is cast on an area of undergrowth (see page 87 of the Dungeon Master's Guide), saves against the spell take a -2 penalty.