Back-up

Eren had honed his proficiency in various elemental spells to a remarkable degree.

He had become a formidable force, capable of matching any Ranker of his generation, even those with deviant elemental compatibility.

However, while he could seamlessly switch between elemental spells without a problem, he knew that doing so during a battle was far from staying mana-efficient. Each transition between different elemental profiles required a significant amount of mana, hindering his overall spellcasting efficiency when it came to mana consumption.

His desire for a solution was clear – Eren yearned for a boundless source of mana that could sustain him regardless of how frequently he switched between elemental spells.

With such an inexhaustible well of power, he could fully unleash the potential of his diverse spellcasting repertoire.