Seal Postern

A mage who has opened a postern through the astral plane may seal it again with this spell. To do so, he must cast this spell while in the same room as one of his posterns. If cast with no argument, this invocation will close the postern in the same room; if instead cast with the 'all' argument, it will seal every portal the caster has in existence. Only posterns created by the mage himself may be thus sealed.