The Greatest Warrior of All Time Returns - Chapter 158

... ordinary mine—it’s a mana vein.”

His words made my eyes widen.

“A mana vein!”

“In simple terms, it’s a mine that forms in regions where the flow of mana follows a massive current. I don’t know the exact principles behind it, but in such areas, you can find high-quality iron and, occasionally, even mithril.”

A leyline—also known as a blood vein of mana.

It’s a general name given to places where a massive flow of mana runs underground.

It seems that ...