Secret Skill

In the Innocence Seekers and Yume ni Aruku series, Secret Skills (奥義 ōgi) are spells or techniques which are specific to a mage or a select few mages. They are exceptionally powerful, and are only known to the most powerful mages. Secret Skills have a wide variety of effects, but the most common type of Secret Skill simply deals massive damage. Other types include buffing (e.g. Mizuki's Wave Augment) and healing (e.g. Sakura's Eternal Blossom).

Details
Like with Full Burst mode, Secret Skills require intense training to unlock. However, once unlocked, it can be repeatedly used whenever conditions are suitable. The conditions suitable for performing a Secret Skill varies with the skill in question (e.g. Yayoi's and Uzuki's Sagitta Aurorae requires a high level of background mana). All Secret Skills can be used in Full Burst mode, unless if they require high background mana levels.

Magical girls do not need much training to unlock Secret Skills, and often already know some. A number of Secret Skills are also tied to a magical girl's Inherent Ability.

Gameplay
In the Innocence Seekers video games, Secret Skills are special techniques or spells which can be used whenever the required conditions are fulfilled or the unit is in Full Burst mode. They consume a portion of the Full Burst gauge when used, but do not consume MP, unless the unit is in Full Burst mode, in which case MP is consumed instead.