Mana Burst (Gem) (魔力放出（宝石）, Maryoku Hōshutsu (Hōseki)?) is a Skill that increases attack power by adding one's excessive magic energy to the weapon; in this case, it is jewels.[1]
Originally, Ishtar’s divine power was free and unrestricted - mostly almighty. But, maybe as an influence of her possessed vessel, for some reason, she is now unable to store her magic energy on anything other than jewels. A powerful Mana Burst Skill, but because the process of charging jewels before firing is necessary, it is quite hard to put it to good use.[1]
