Shinji's decision to publicly disclose information about Caster was purely out of desperation.
After a night of chasing, he regretfully realized that relying solely on Scathach was not enough to kill Caster.
The combination of the former French marshal and the criminal genius may not have overwhelming strength, but they were cunning enough.
After losing their workshop, Caster and Uryuu Ryuunosuke became more cautious in their actions. Caster reduced the scale and frequency of his magecraft usage, while Ryuunosuke employed skills that had never been suspected by the police, such as erasing traces and setting up false leads. In the end, they managed to escape Scathach's pursuit.
Scathach only knew that the two hadn't left Fuyuki City but couldn't pinpoint their exact location.
Although Scathach, as a Servant, was far less powerful than her true form, her experience of over two thousand years remained. The fact that they could elude her pursuit indicated the troublesome nature of this extremely wicked duo.
Now, Shinji couldn't sit still. He didn't want to say anything grandiose like "Every day delayed could result in more victims." He simply didn't want to witness the scenes he saw last night again.
To kill the Caster group as soon as possible, he needed more Masters to get involved.
At this point, the Church issued a signal, and Father Risei's judgment did not disappoint Shinji, but it wasn't enough.
Most Masters with a background in magecraft were cautious, prioritizing their safety and not easily taking action without sufficient certainty.
Under normal circumstances, after a supervisor changes the rules, the first thing to do is gather information about Caster, understand their data and fighting style, and then consider the timing to intervene.
However, Caster has only clashed with Scathach so far, and the other Masters have no relevant information about Caster. If they want to obtain information, they can only send their Servants to probe. And this "probing" not only exposes Caster's strength but also the strength of the vanguard Servant. Which Master would be willing to bear this risk?
The worst-case scenario is that no one wants to stick their neck out, and they keep dragging on while Caster and Uryuu Ryuunosuke continue their crimes. After all, in the eyes of most magus, the lives of ordinary people are worthless, and it doesn't matter if a few die.
This is not what Shinji wants to see. The sooner Caster and Uryuu Ryuunosuke die, the better.
Therefore, he needs to step up his game—by directly exposing the information, first, to reduce the time Masters spend gathering information; second, to avoid unnecessary suspicion; and third, to create the impression of being "foolish" to other Masters, making them underestimate him.
With enough information, Kenneth, who has already used up one Command Spell, will certainly take action. Waver, who still possesses the enthusiasm and sense of justice of a young person, won't fall behind either. And Tohsaka Tokiomi won't miss this rare opportunity—not only from the perspective of a local overseer but also with deeper calculations in mind.
Archer, possessing the skill "Independent Action" at A rank, is the Servant least inclined to follow the Master's orders. If he feels like it, he will act; if he doesn't feel like it, he won't. To make Archer do something, Tohsaka Tokiomi can only advise him as a vassal or use Command Spells.
To make Archer retreat last night, Tohsaka Tokiomi had already used one Command Spell, leaving only two. Compared to six enemies, it's too few. He needs more Command Spells to counterbalance Gilgamesh.
The only ways to obtain Command Spells are either by taking them from other Masters or being bestowed by the overseer.
However, this additional bestowal cannot be done openly and cause public outrage. Both of them need a suitable excuse.
Caster's violation happens to provide the perfect excuse. As long as Archer can deliver the final blow to Caster, Father Risei can then bestow all of his remaining Command Spells to Tokiomi.
With so many Command Spells in hand, Tokiomi Tohsaka can regain control as the Master without having to tolerate Gilgamesh's whims.
Of course, there are always variables in things that haven't happened yet. If Caster dies at the hands of another Servant, Father Risei would still bestow additional Command Spells—though he never mentioned how many additional Command Spells would be given.
Shinji is well aware of the calculations between Risei and Tokiomi. He certainly won't sit idly by while Tokiomi gains such a huge advantage.
The coercive power of Command Spells on Servants varies depending on the specific nature of the command. The more specific the command, the stronger the coercion. For example, Kenneth's command to Lancer, "Help Berserker and kill Saber," is an order that Lancer cannot disobey and must follow.
Conversely, the more vague the command, the weaker the coercion. Instructions like "absolute obedience to the Master" can be exempted if the Servant resists even slightly.
In addition, the coercive power is enhanced with each use of a Command Spell. The coercion of two Command Spells is stronger than that of one, and three Command Spells are stronger than two. By this logic, if Tokiomi possesses a dozen or more Command Spells, even a loose command like "absolute obedience to the Master" can be achieved, and even the mighty Heroic Spirit Gilgamesh would be unable to resist.
How terrifying would Gilgamesh be if he were always obedient, following orders, and in a state of constant seriousness? Shinji can't help but shudder at the thought.
If it comes to that, he can only rely on Scathach, burdened by the Assassin class, Lancelot, who can restrain "The King's Treasure," and King Arthur, who has regained Excalibur. Perhaps they would have some chance of success.
Under no circumstances can they allow Gilgamesh to become like that. Shinji believes that Gilgamesh himself wouldn't want to become that way either.
So, it's time to make a move. His and Berserker's mission is to keep a close eye on Archer and prevent him from landing the final blow.
And finally, Saber.
As a seasoned Type-Moon fan, Shinji considers himself to have a good understanding of Saber. However, the control of the situation is not in Saber's hands but in the hands of his Master, Kiritsugu Emiya—the person Shinji finds most difficult to comprehend.
Shinji admires his pursuit and fears his methods.
Luckily, Shinji has one more ally, Justeaze, the founding ancestor of the Einzbern family. She has already found the Einzbern's base of operations. With her presence, Shinji doesn't have to worry about Kiritsugu Emiya backstabbing him while dealing with Caster.