Level: Dread Necromancer 9
Components: V, S
Casting Time: 1 standard action
Range: 20 ft.
Area: 20-ft.-radius burst centered on caster
Duration: Instantaneous
Saving Throw: Will half; see text
Spell Resistance: Yes
Mass harm charges all subjects with negative energy that deals 1d12 points of damage per caster level (to a maximum of 20d12 points at 20th level). If a creature successfully saves, mass harm deals half this amount, but it cannot reduce the target’s hit points to less than 1.
If used on undead creatures, mass harm heals it by a like amount instead.
Source: Heroes of Horror, page 130.