Arise Of Mistress Death

A world plunged in darkness, arising with the opening of the underworld, it unleashed creatures otherworldly, many perished and lost there lives, however with the opening of these mysterious holes came what we now call classes, different abilities, after a while we had stopped the ongoing clash of creatures, but how long can we contain this power. (Note:this book is literally just a huge fan copy of solo leveling, I'm sorry but I just really liked Solo leveling and wanted to write a story that was similiar to it, sorry to the people who hate that I'm doing this in advance, but this is just my wild imagination running together)