By tracing the mystic runes upon a book, map, scroll, or similar instrument bearing written information, the magic-user prevents unauthorized reading of such. The explosive runes are difficult to detect, 5% per level of magic use experience of the reader, thieves having only a 5% chance in any event. When read, the explosive runes detonate, delivering a full 12 to 30 (6d4 + 6) hit points of damage upon the reader, who gets no saving throw, and either a like amount, or half that if saving throws are made, on creatures within the blast radius. The magic-user who cast the spell, as well as any other magic-users he or she instructs, can use the instrument without triggering the runes. Likewise, the magic-user can totally remove them whenever desired. They can otherwise be removed only by a dispel magic spell, and the explosive runes last until the spell is triggered. The instrument upon which the runes are placed will be destroyed when the explosion takes place unless it is not normally subject to destruction by magical fire.