Places a magical shield around the target that boosts magic defense.Description
Shell is a potent and relatively inexpensive buff that halves magic damage. Against enemies that rely on spell damage, Shell is especially useful to cast, particularly on characters with low Magic Defense or low HP. Because the spell can only be used on one target at a time and costs a turn to use, it should be reserved for long battles.
The spell protect grants the protect effect, which does the same for physical damage. Protect should be used when enemies rely more on physical damage. Aside from Shell, the Reflect spell can be cast to cause magic spells to reflect back against the enemy, for a slightly higher MP cost. This protects against far more offensive magic spells, but also prevents curative spells from being cast against them, and only works against certain spells. However, it can situationally be a better way to avoid magic damage.
Because the Shell spell is not improved or weakened by the caster's stats, it can be taught to and used by any party member. In fact, it may be better for non-spellcaster party members to use Shell on their allies, allowing spellcasters to preserve their MP for offensive or healing spells where their MP is more important.