It was impossible for a human being to directly absorb the magic power stored in a brick of magic power.
The process had to be guided with one's mental power, which could take a long time.
In order to improve the absorption speed, one had to build a floating city with the bricks to create a large area of Magic Power Affluence. Then, one had to contain and compress the magic power with magic arrays to prevent it from leaking.
In such a way, the master of the floating city would have a piece of legendary "equipment" that could quickly replenish his mana, fly in the sky, and serve as a sturdy stronghold.
He would be the best in terms of offense, defense, duration, and mobility.
Having such a thing in the main plane would almost be like cheating.
The bricks of magic power, as the fundamental materials to build a floating city, each contained an enormous amount of magic power and didn't have any side effects.
