At the tower, there are several magic factions, represented by their respective element and color.
Elfie was ready to scout Will the second he stepped foot inside, but the tower insisted he had to pass a test first. A test all mages who aren't immediately assigned have to take. The bloom.
During this trial, Will and his other unassigned classmates had to face off against Zuptonias, monsters produced by the tower. And these things are not a joke. Yet Will just slashed them apart with pure brute force. He then proceeded to intercept an out-of-range ice attack by Julius in order to prime his sword, which allowed him to fully charge it into Glaus Wis, giving him an ice move set including the Glaus Mill. Instantly, he Load Bursted and destroyed all of the Zuptonias.
He was aura farming in front of all the Magia Vander. They all pleaded to have him in their faction.
Will was proving himself here, but not everyone was pleased. In fact, Kritz, the paramount of the upper institute, was insistent that Will had failed, because he cannot use Wis on his own. He needs another mage with him to use such strength, making him a liability to the tower. That was the answer Kritz gave to everyone.
But Kritz is actually insane. He wants to dissect Will in order to artificially recreate Wis, because this power is a freaking anomaly.
So this man initiated another test for Will, a fight against another monster, the gelatinous crystal wraith, which can only be killed with magic. However, this time Will had to fight alone.
The result was a complete, one-sided failure.
Luckily for Will, he was given a grace period of a week before another bloom. But in the next trial, if he couldn't activate Wis on his own, he could not join any faction and ascend the tower.
Julius, being such a good guy, offered to help him train, but it didn't get very far, until a mysterious outcast named Caridwen arrived, who secretly turns out to be Headmistress Cauldron in disguise.
It was here, as Caridwen, that she told Will how his body works. Currently, Will knows how to store magic deep inside of him, but he is unable to expel it. Hence why he relies on priming himself with magic only from an external source.
However, with Caridwen, Will underwent his next biggest level up: Prime Pathos. By awakening the story of magic written in his blood and his memories, he would be able to relive magic he had once primed.
Just like before, Will's true magic lies in its origin. The more he understands himself and his past, the more he is able to control Wis.
So Caridwen used her magic to take Will into his old memories, back at the orphanage, where Will finally remembered and relived the first time he had used Wis to save Elfie as a child. It was here that Will gained the ability of reloaded Wis, which is way harder to maintain, because instead of borrowing external magic, Will uses internal emotional energy directly to open his book of memories, reaching deep inside of his own story and retrieving the spell he once used.
Even so, Finn helped the dwarves get their hands on the Wis gem specifically for this reason, since the sword would supplement what Will lacks.
Regardless, this level up allowed him to use Tidus Wis by himself during the second bloom, gaining the attention of not just Elfie, but another Magia Vander, Zeothorus Rainbolt.
As a salty critic who still refused to accept Will's magic, Zeo gave him another chance. If Will could tank an attack from him, he would accept him.
And Will did exactly that. He simply absorbed the spell, eating Zeo's thunder attack and acquiring Zalgias Wis.
So Will could finally be with Elfie and live happily ever after, right?
No. The thing is, now Zeo wanted Will, and he wasn't taking no for an answer, even up against a full-powered, furious Elfie, who just wanted her man.
Surprisingly, Finn, who of course was watching from the sidelines, thought Zeo was a much better suited teacher for Will. Unlike most characters, Zeo's fighting style has a lot of punches and close-range combat, completely opposite to most mages, who rely on long-distance attacks, meaning he is one of the only few people in the world who can properly teach Will these uses.
But the funniest part is that the entire conflict over Will's future got settled by rock, paper, scissors, after Adam intervened. The king of the Magia Vander himself.
And so Zeo won.
Being in the Thunder faction worked out pretty well, considering they are all hardcore about working out. It is only with them that Will was pushed to his physical limits, breaking the running record of one thousand six hundred laps. And that was just a warm-up, before Will was put up against Zeo as a sparring partner literally every single day.