Whisper's Helpful Portal
(Alteration)

Range:  60 yards
Components:  V, S, M
Duration:  Special
Casting Time:  7
Area of Effect:  3?10 feet area
Saving Throw:  None

This spell is an improvement of the teleport spell. Instead of opening an instantaneous conduit from one place to another, this spell creates a portal that stays open until the caster wills it away, it is dispelled or one creature per level of the caster has passed through. Note that to pass first one way, then back by the same creature counts as two passes.
This spell allows the caster to flee to get help from the other side, or take a short breather on the other side before coming back. However, the portal manifests itself as a shimmering silver plane, and anyone who wants to can pass through as long as it is activated. Hence it is not a good way to flee from pursuit, as the pursuit can follow through the portal as well, since the caster has to concentrate for some ten seconds to close the portal.
For success in anchoring the portal, the same rules apply as a regular teleport, thus caster beware, you might be in for a fall, or end up encased in stone. However, if the first one through runs into solids, that material will end up in front of the portal on the opened end (the portal replaces the volume attempting to pass with equal volume from the other side). Some DM discretion will be needed with the possibilities this poses.
The material component is a small (3 inch) mithril rod, treated in such a way as to be easily broken. At the end of the spell casting, the caster breaks the rod, and the portal appears. Note that the rod does not disappear, but once broken cannot be reused for this spell.

