Chapter 120- Forms Of Magic (Part 2)
"Everything in existence has a mana core as I explained before. Even our own world has its mana core inside it that generates the world's mana. So, if there is anything that could determine whether you can be a talented mage or nothing but an ordinary person, it's this."
After that, Emilia changed her tone a little bit to a more mysterious one.
"Now, ignoring the fact that you can actually gain powers merely from killing monsters, the only real and logical way to become stronger is through this." She said as emphasized the two words 'Real' and 'Logical'.
Then, she pulled out a mana core of a random monster from her spatial ring and showed it to Rin.