True Banishment

(Tome of Magic)

Level: Cleric 8,
Components: V, TN,
Casting Time: 1 standard action
Range: Close (25 ft. + 5 ft./2 levels)
Target: One extraplanar creature
Duration: Instantaneous; see text
Saving Throw: None
Spell Resistance: Yes

You thrust your holy symbol at the creature as you speak its truename, sending it back whence it came in a swirl of flame and
This spells functions like the banishment spell, except that it requires a successful Truespeak check to function and allows no saving throw (spell resistance still applies, though).
The true banishment spell affects only a single creature, but there's no Hit Dice limit other than the one implicit in the Truespeak check DC.
Objects that the target hates, fears, or opposes don't grant bonuses on the level check to overcome the creature's spell resistance.
If true banishment is successful, the target cannot return to the plane it was banished from for one month per caster level—unless it learns and correctly speaks the spellcaster's personal truename, in which case the prohibition no longer applies.
Truename Component: When you cast this spell, you must correctly speak the personal truename of the creature you're trying to banish.