Elemental Seal

Elemental Seal is a job ability available to Black Mages who reach 15th level or greater in Final Fantasy XI. It can only be used once every 10 minutes. When activated it will increase the potency of the next black magic spell cast. If this is a damage spell this could potentially increase the quality of damage significantly.

It also has the effect of making black magic spells less resistable. For this reason, it is often used in conjunction with spells that are not damage related, such as Sleep spells. Since it makes the spell less resistable, the enemy creature is less likely to have a full or partial resist (which would lesser the duration of the sleep). Since sleep spells create a lot of emnity that is undesirable and very potentially deadly for mages, it is best to sleep the creature on the first try.