Phase Door

When this spell is cast, the wizard attunes his body, and a section of wall is affected as if by a passwall spell. The phase door is invisible to all creatures save the spellcaster, and only he can use the space or passage the spell creates, disappearing when the phase door is entered, and appearing when it is exited. If the caster desires, one other creature of man size or less can be taken through the door; this counts as two uses of the door. The door does not pass light, sound, or spell effects, nor can the caster see through it without using it. Thus, the spell can provide an escape route, though certain creatures, such as phase spiders, can follow with ease. A gem of true seeing and similar magic will reveal the presence of a phase door but will not allow its use. The phase door lasts for one usage for every two levels of experience of the spellcaster. It can be dispelled only by a casting of dispel magic from a higher-level wizard, or from several lower-level wizards, casting in concert, whose combined levels of experience are more than double that of the wizard who cast the spell (this is the only instance in which dispel effects can be combined). Rumor has it that this spell has been adapted by a certain powerful wizard (or wizards) to create renewable (or permanent) portals, which may (or may not) be keyed to specific individuals (henchmen) or items (such as rings).