Thanks to the books in Heinz's laboratory, Vale learned plenty of Dark Spells even before he attended Professor Morton's class.
It means that he had a long time considering the spell that he would like to learn inside the Academy.
Furthermore, Vale actually felt helpless after hearing the Professor's suggestion, he only wanted him to write at least six Dark Spells.
However, as he entered his Phantasm State, he can see 12 Available Spell Lights!
That's right, aside from the four Spell Models in his body, he can see 12 other bright lights indicating that he can learn 12 more spells. Furthermore, he knows that this number can still increase since he hadn't reached his limit yet.
According to Master Heinz, the Spell Lights will only stop appearing at around 18 years old.
He still has about 4 years to accumulate Spell Lights!