Juventas

Juventas (ジュベンタス Jubentasu) is a Sky Dragon Slayer Magic Spell.

Description
A spell unique to Sky Dragon Slayers. By gathering pure air from the atmosphere, the user mixes it with their own magical power, imbued with the energy of a Sky Dragon Slayer. Doing so converts the air into a shimmering aura of light, which the user takes into their body. From there, this aura begins to work as a rejuvenation agent, regressing the user to a different age of their choosing. While this can naturally be beneficial when used by a user who has long since reached old age, it also has its uses as a power conservation form; this, in fact, is the primary reason Lorensael uses Juventas, suppressing her magic power as well as giving her a lighter form that is fit for speed. Juventas, however, also cuts the users physical strength and durability, due to their younger, child-like body. The spell itself is permanent until the user chooses to reverse it, even falling unconscious or asleep, the spell remains active without draining the user's magical power or requiring concentration.

Trivia

 * Juventas is the Roman name for Hebe, the Greek God of Youth.