Portal Barricade(Underdark, p. 60)
Level: Portal (Alternative) 5,
Components: V, S, DF,
Casting Time: 1 standard action
Range: Close (25 ft + 5 ft./2 levels)
Target: One portal
Duration: 1 hour/level (D)
Saving Throw: None
Spell Resistance: No
Portal barricade temporarily closes a portal and prevents it from functioning for the duration of the spell.
Knock spells, chimes of opening, and similar effects cannot end or suppress a portal barricade, though dispel magic can negate it.