Portal view

Portal view was a divination spell that allowed people to see through portals.

Effects
As a general rule, portals were invisible and it was not possible to see what the other side of a portal looked like. Mundane methods like sticking the head into a portal did not work, a person who tried such a thing was immediately sent to the other side. The portal view spell made it possible. It made one side, the side the caster was, transparent, thus allowing people to see where the portal led to. What this spell did not establish was the possibility to affect the destination. For example, one could not one-sidedly send a spell through the portal.

Components
Portal view required somatic and verbal components, a focus, a divine focus when cast by a divine spellcaster, a glass eye when cast by an arcane spellcaster, and ten minutes to cast.

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