The Villain Wants to Live악당은 살고 싶다

Oh thanks, I've heard a bit about it before but I'll make sure to check it out!

So to give a general idea, the world of magic in this novel is kind of hard to say specific rankings because it hasn't defined it too well. There are pinnacles like Arch Mage or being an Elder of a new branch of magic that hasn't been discovered before. There are the typical elements like fire, earth, wind, water, etc... but it can branch out to more stuff like auxiliary, manipulative, augmentation, etc... so it gets specific there. (This is only how the magic works in this world).

The MC himself though gets stronger through participating in story events (like main story quests in MMOs) and gets an increase in his mana (albeit slightly) or being available to choose his rewards from either a shop that players would usually only have access to, not the NPCs of this world (he uses his points to get an increase in his mana quality). Or, he would get the ability to utilize another kind of magic or increase the typing of his magic, improve upon old ones, etc... The other way to do it is that he also uses his ability "Understanding" to improve his understanding/comprehension of his magic to improve it and make it more efficient (eventually where he just implements something [I won't spoil] to reduce the cost it has on his mana and to also improve its efficacy).

Keep in mind though, Decluein canonically before the MC transmigrated had very little mana and actual power with his magic, so the improvements he makes are mostly qualitatively or improve his current range of expertise in magic or reduce the costs of said magic.

TLDR - he gets stronger through story quests, reducing his magic cost and improving both the efficacy + efficiency of his magic.