Sigils of Suppression

A globe of invulnerability fills the entire stronghold space, as represented by the arcane sigils that are inscribed upon the walls. No spell effects of 4th level or lower function within this space. Such spells cannot be cast within the space, nor can their effects extend to within the space (though a targeted dispel magic can suppress the effect as with any other magic item).

Caster Level: 11th; Prerequisites: Craft Wondrous Item, globe of invulnerability; Market Price: 33,000 gp.