Portal View(Underdark, p. 60)
Level: Bard 4, Sorcerer 4, Wizard 4, Spellthief 4, Portal (Alternative) 3,
Components: V, S, AF, DF,
Casting Time: 10 minutes
Range: Close (25 ft. + 5 ft./2 levels)
Target: One portal
Duration: 1 minute/level
Saving Throw: None
Spell Resistance: No
Portal view makes a portal transparent from your side only for the duration of the spell.
It does not actually open the portal, so no line of effect is established, but it does enable line of sight.
Portal view does not reveal any of the portal's special properties (such as one-way or creature-only); it only allows creature on your side to view the portal's destination.
Arcane Focus: A glass eye.