Global Awakening: I, The Weakest Awakened, The Skill-Maker!

Rain regressed in the past to where he was still a high school that joined Hunter Academy. As a kid, he was always on the sidelines and was just a support to the heroes in his past. But this time, he awakened a class and that was the class Skill maker!
With his powers, he will support the heroes to become stronger than before. With his hobby of creating skills, he made one skill after another.
In this world, dungeons were spawned and Hunters would kill the bosses inside to eradicate them entirely. If not, there would be dungeon breaks and monsters would break out to the surface.
With Rain, he would eradicate all dungeons once and for all!