Curse of the Brute

(Defenders of the Faith: A Guidebook to Clerics and Paladins)

Transmutation
Level: Paladin 2, Cleric 3,
Components: V, S,
Casting Time: 1 action
Range: Touch
Target: Creature touched
Duration: 1 round/level
Saving Throw: Fortitude negates
Spell Resistance: Yes

You can grant an enhancement bonus up to +1 per caster level to one physical ability of the creature touched (Strength, Constitution, or Dexterity).
However, this temporarily suppresses both the creature's Intelligence and Charisma, each by the amount of the enhancement bonus.
If this lowers any ability below 3, the spell fails.
Thus, a 5th-level cleric might cast curse of the brute on a barbarian to increase the barbarian's Strength by 4 points.
Doing this increases the barbarian's Strength by 4 points but lowers his Intelligence by 4 points and his Charisma by 4 points.
If the barbarian's original Intelligence or Charisma was 6 or lower, the spell would fail without effect.