This skill is most commonly used shortly before a battle, allowing enough time for the casting cost to be regenerated. Then large spells (10, 15, or 25 energy, for example) are cast, Mantra of Recall ends and refills your energy bar.
Unlike all other Mantras, Mantra of Recall is an enchantment spell, instead of a Stance.
Beware of using Enchantment duration increasing weapon upgrades in combination with this spell. The added duration means you will gain the energy boost from Mantra of Recall later than originally intended.
Recasting Mantra of Recall while Mantra of Recall is still active renews the duration but does not return energy.
This presumes Mantra of Recall is cast as often as possible (activation + recharge time) before any activation/recharge time modifiers in conjunction with ending prematurely.