The magical mirror-egg spell is a creation Kethry devised based on the concept of the mirror-egg used in Gift training. In this variation, the trap-spell forms an egg-shaped shield around the target, reflecting magical energy back at him. In other trap-spells, the trapped mage just has to patiently search until he finds the keypoint of the spell, and cut his way through it to collapse the spell. That technique won't work here, as any attempt would be reflected back. The song "Mirror Spell" is about Kethry casting this on Raschar's mages.