Vow of Silence

Secret rite of the black-haired witch Velka. Prevents casting of magic within effect area.
Velka, the Goddess of Sin, is a rogue deity, but she is versed in arts both new and old, and is considered to have a great range of influence even as gods are concerned.

With a crackling of purple light, you create a 30ft radius around you where no spells can be cast except by creatures with legendary actions.