The World's Strongest Mage? Sorry, He's My Apprentice

(Invincible + no harem + magic + high martial arts + alternate world + urban)

The strongest mage in City A can single-handedly sweep away the armies of every nation in the world, and venture alone and unharmed into the forbidden lands beyond the realm, the Ancient Secret Realm... And someone this powerful is actually Fan Yi's apprentice.

The ninth-tier transcendent magic that exists only in theory is something he casually conjured up?

During a world war, Fan Yi used his extraordinary martial arts to single-handedly sweep through the armies of every nation. After spending years activating the “Unknown,” which could make people immune to martial artists' attacks, the people of America saw Fan Yi smile and casually raise a hand to cast a ninth-tier transcendent spell.