SRD:Darkskull

Darkskull: This skull, carved from ebony, is wholly evil. Wherever the skull goes, the area around it is treated as though an unhallow spell had been cast with the skull as the touched point of origin (except that no additional spell effect is tied or fixed to the darkskull).

Moderate evocation [evil]; CL 9th; Craft Wondrous Item, unhallow, creator must be evil; Price 60,000 gp;Weight 5 lb.