As it turned out, only a thought was required.
A notification appeared.
[100 EXP consumed. Wizard class level up to 2. Congratulations, Host! You are now a Level 2 Novice Wizard.]
[You've gained 1 stat point.]
[Your soul power production rate has increasd.]
[Your arcane heart has expanded. Now you can store more soul power in it!]
Val could feel the arcane heart within him expand, now big enough to hold more soul power. The limit of soul power he could store in his arcane heart was now 200 units.
Simultaneously, the rate at which he produced soul power increased to 20 units per hour. An additional stat point appeared, bringing his total to 5.
The interface updated the requirement for the next level of his wizard.
1k EXP was required to level up the wizard class to level 3!