Portal barricade

Portal barricade was a transmutation spell that barricaded a portal for the duration.

Effects
On casting portal barricade, a portal stopped working for its duration that was counted in hours. Barring successfully dispelling it, no means, including knock spells or chimes of opening, could return them to functionality.

Components
Casting portal barricade required somatic and verbal components as well as a divine focus.

History
At latest by 1372 DR, a magical staff called a staff of portals was invented in the Underdark that required the portal barricade spell to craft and could be used to cast the spell too.