The Eternal Bottle was a Legendary item that was frighteningly effective in the hands of a powerful Legend Wizard.
From what Marvin knew, this item had at least two functions:
First, it had the ability to absorb Chaos Magic Power. As long as you had the incantation, the Eternal Bottle could absorb a great amount of Chaos Magic, storing it away.
Second, it could be used to instantly replenish Chaos Magic Power. A Wizard wouldn't have to rest to recover his Magic Power if he had the Eternal Bottle in hand. This was like a supplemental pool that could be drawn from.
Some large-scale Legendary Spells used up a lot of Magic Power, creating a huge burden on Legend Wizards. Without the help of certain tools, a caster's will could collapse if they didn't have enough power.
The Eternal Bottle was no less important to Legend Wizards than Nightfall was to the Shadow Prince.
