Roy was a level 1 apprentice.
To reach the next level, he needed to increase the size of his Magic Sea.
Currently, it could only contain 20 wisps of mana.
That was its maximum capacity.
As he had read the novel, he knew that a peak level 1 apprentice could contain ten times that amount in their magic sea, and he also knew various ways to increase its size.
Learning a meditation technique that uses energy present in nature, oneself, or magic herbs to nourish the Magic Sea was the first method for a mage to increase the size of their Magic Sea.
The problem with this was that it required the mage to have patience and time, a lot of it.
If he were to put it into practice, he would need to go into seclusion for weeks in order to advance to the next level.
But… he didn't have that much time to waste!
Thus, he decided against it.
The second method was for him to absorb Mana using his meditation technique and release it by activating the magic spell model repeatedly.