Level Gacha: It Turns Out the Dump Stat "Luck" is the Most Important

It's been ten years since dungeons appeared on Earth. And one man was weak because he would not grow even if his level went up. He felt there was a possibility in the "Luck" stat that was ignored by everyone because it wasn't directly related to strength, and poured his growth into this one stat. In the end of this tenacity, he found a strange skill that let him spend levels to earn something.