The Doom spell gives one creature a -2 penalty to all rolls including THAC0 and saving throws.
In-game description Edit
Note: Spell descriptions sometimes differ significantly from the actual in-game implementation.
This spell causes a feeling of doom to overwhelm the target. For the duration of the spell, the target receives a -2 penalty to all his or her rolls, including THAC0 and Saving Throws. There is no Saving Throw for this spell.
(Alteration) Level: 1 Sphere: Charm Range: 25 ft. Duration: 1 turn Casting Time: 9 Area of Effect: 1 creature Saving Throw: None