You can sicken creatures with your spells.
BENEFIT
You can modify a spell to sicken a creature damaged by the spell. When a creature takes damage from this spell, they become sickened for a number of rounds equal to the original level of the spell. If the spell allows a saving throw, a successful save negates the sickening effect. If the spell does not allow a save, the target can make a Fortitude save to negate the sickening effect. If the spell effect also causes the creature to become sickened, the duration of this metamagic effect is added on to the duration of the spell. Spells that do not inflict damage do not benefit from this feat.
MP Increase: +2 (a sickening spell costs 2 additional MP more than the actual MP cost of the spell.)