Blackmantle

Blackmantle creates a shimmering aura around all creatures within the affected area that negates all healing and regeneration, both natural and magical. For instance, a potion of healing has no effect on a creature under the influence of blackmantle, a troll cannot regenerate lost hit points, and Cure Light Wounds is useless.
Blackmantle is negated for any target creatures who make successful saving throws. Otherwise, it persists for 1 turn per level of the caster. If the creatures are still alive at the end of the spell's duration, any active curative forces will operate normally; for instance, a ring of regeneration will resume its function. However, consuming a potion of healing or applying a staff of curing while blackmantle is in effect will have no effect, since these types of magic work instantly. In such cases, the dose of potion of healing and the charge from a staff of curing are not only wasted, but the aura generated by blackmantle actually negates the potion of healing or the staff of curing, rendering it useless. If a potion of healing or staff of healing is applied after the spell wears off, the healing magic works normally.

[Complete Wizard's Handbook]

School: Necromancy, Enchantment/Charm
Level: 6
Rarity: Common

Range: 60 yards
Components: V, S, M
Duration: 1 turn/ level
Casting Time: 1 round
Area of Effect: 15-foot radius
Saving Throw: Negates

Material Components:
a small mummified animal, such as a mouse or a toad