Level: Sorcerer 4, Wizard 4
Components: V, S, M
Casting Time: 1 round
Range: Close (25 ft. + 5 ft./2 levels)
Target: One humanoid creature/level, no two of which can be more than 30 ft. apart
Saving Throw: Fortitude negates
Spell Resistance: Yes
This spell causes instant diminution of humanoid creatures, halving their height, length, and width and dividing their weights by 8. This decrease changes each creature’s size category to the next smaller one. Each target gains a +2 size bonus to Dexterity, a –2 size penalty to Strength (to a minimum of 1), and a +1 bonus on attack rolls and AC due to its reduced size.
A Small humanoid creature whose size decreases to Tiny has a space of 2½ feet and a natural reach of 0 feet (meaning that it must enter an opponent’s square to attack). A Large humanoid creature whose size decreases to Medium has a space of 5 feet and a natural reach of 5 feet. This spell doesn’t change a target’s speed.
All equipment worn or carried by each creature is similarly reduced by the spell. Melee and projectile weapons deal less damage (see Decreasing Weapon Damage by Size). Other magical properties are not affected by this spell. Any reduced item that leaves a reduced creature’s possession (including a projectile or thrown weapon) instantly returns to its normal size. This means that thrown weapons deal their normal damage (projectiles deal damage based on the size of the weapon that fired them).
Multiple magical effects that reduce size do not stack, which means (among other things) that you can’t use a second casting of this spell to further reduce the size of as humanoid that’s still under the effect of the first casting.
Mass reduce person counters and dispels mass enlarge person.
Mass reduce person cannot be made permanent with a permanency spell.
Material Component: A pinch of powdered iron.
Source: Player’s Handbook (version 3.5), page 269.