This spell strengthens the magical power of the caster's spells, making them more difficult to resist. Spells cast during the duration of the Greater Spell Fortification are exceptionally forceful, resulting in a -4 penalty to saving throws vs their effects. Also, there is a -20% chance to any magic resistance checks made against fortified spells.

Spells to be fortified must be cast during the duration of this spell; if this spell's duration ends before the to-be-fortified spell is completely cast, that spell functions at normal levels. The saving throw penalty is cumulative with other penalties, such as a specialist's saving throw penalty. Note that a fortified spell's saving throw penalties apply to both creatures and objects; items would make their save vs magic fire at -4 versus a fortified Fireball.

Note: the Spell Fortification spells are both different and previous to the existence of the Malison spells presented in the Tome of Magic. My creations affect the caster and his spells directly, making the spells tougher, while the ToM spells enchant the target creatures, making them effectively weaker. My creations are hence Metamagic-oriented, while the others are merely enchantment/charms that have a simiar effect.