My "1,000% EFFICIENCY" Skill Lets Me Learn Any Spell In Just One Second!

My "1,000% EFFICIENCY" Skill Lets Me Learn Any Spell In Just One Second! What happens when a supposedly useless skill hides the power to master any spell in a single second? Kael Vale is mocked as a failed mage, betrayed by his family, overshadowed by his gifted brother, and condemned by the people he once protected. But after death reveals the true form of his “One Thousand Percent Efficiency” skill, Kael returns to the past with perfect memory, unlimited learning potential, and a ruthless plan for revenge. While everyone celebrates Darius as a legendary fire genius, Kael quietly learns forbidden magic, repairs cursed artifacts, builds an invincible fortress, gathers abandoned talents, steals hidden resources, and transforms basic utility spells into god-level weapons. Every insult becomes motivation. Every betrayal becomes evidence. Every opportunity his enemies greedily seize becomes another poisoned gift. This dark fantasy manhwa recap delivers regression, overpowered protagonist progression, magic academy rivalry, hidden power, system awakening, revenge, betrayal, face-slapping, kingdom building, secret training, powerful skills, and satisfying karma. Watch Kael evolve from a humiliated outcast into an unstoppable archmage who defeats an ancient disaster with one basic spell, then forces his arrogant brother, toxic family, corrupt teachers, and faithless fiancée to face the consequences of everything they did without mercy or forgiveness.