Conformance

The conformance spell has a simple principle with a profound effect: probable events always manifest.
In game terms, this means that events with a probability of 51% or better always occur. Thus, if a saving throw of 9 is required to avoid an effect, no roll is necessary; the save is automatically successful. If a warrior must roll 10 or better to hit an enemy, he automatically hits.
Conversely, improbable actions (those with less than a 50% chance) always fail. If a warrior must roll 12 or better to hit an enemy, he automatically fails. If a thief's chance to hide in shadows is 49%, he automatically fails.
There are two conditions that affect this spell. First, a Prayer spell is continuously operative in the area of effect, shifting the balance of combat probabilities toward the favor of the priest who casts this spell and his companions. Second, probabilities of exactly 50% always shift in favor of the spellcasting priest. For example, if a roll of 11 or better is needed to save against a spell effect, this is a 50% chance for success. In such cases, the priest and his friends always make the save and enemies always fail.
This spell is particularly potent if Bless and Chant spells are cast in the area of effect.

[Tome of Magic]

Sphere: Law
(Conjuration/Summoning, Invocation)
Quest

Range: 0
Components: V, S
Duration: 6 turns
Casting Time: 1 round
Area of Effect: 80-foot-diameter sphere
Saving Throw: None