if he wants to level up his other skills without the use of his two big skills then he should go back to floor one and only use his other skills. not go fight the boss the next boss.
1. Seems like this story is falling into the "read like a novel" trap. They're explaining stuff that doesn't need to be explained because it's a visual media unlike a novel which needs to be descriptive for the imagination. Re: Monster is the worst offender of this.
2. If you want to increase your swordsmanship you DO NOT go and fight even stronger enemies. You go back and fight weaker ones. The stronger enemies get, the more skills you need to
use. That's MMO 101 fam.
So, the reason why his shadow magic mana consumption is so intense is because it tries to preserve as much magic as it cans for emergency situation. Hmm... Interesting
I'm guessing the chick on the cover has to do with his shadow magic? That's gonna be disappointing if so, I was really hoping the heroine would have more substance.
10th floor: Goblin General
20th floor: Random Orc, lol
30th floor: Random Wolf, lol
40th floor: King of the goblins, the weakest monters
50th floor: Fenrir, monstrous wolf that bit off a god's hand and will one day swallow the sun and devour Odin himself.