assassin prana emission

Stepping unauthorized into the bounded fields is all but safe, all the more for the large mass of prana that is a Servant. Essentially, even if it is a spiritual body, it should be just about impossible to slip through the bounded fields of the fortress undetected.

However, the impossible can always be made possible. That is the Presence Concealment skill of the Assassin class. While he does not excel in battle power, Assassin can suppress his prana emission until it reaches zero to creep in the shadows and reach his target.

Additionally, for the Assassin of this time, Kotomine Kirei's Servant, this night's infiltration operation was especially easy. The garden he was now sneaking in isn't the one in the Matō mansion that has been considered enemy territory for some time. It is the mansion of Tōsaka Tokiomi, who was his Master Kirei's ally until just yesterday. Of course, Assassin too has agreed with Kirei and Tokiomi to deceive the other Masters and remain undercover. Obeying that secret agreement, he has undertaken the guarding of the Tōsaka mansion on countless occasions. Knowing all about the disposition of the bounded fields, he was naturally aware of the blind spot.

In his spiritual form, Assassin progressed through the many alarm fields without a problem, laughing at the ironic fate of Tōsaka Tokiomi. That arrogant magus has placed a considerable faith in his protégé Kirei, but can't imagine that he might be bitten by his dog.

- Fate/Zero: Act 2 Part 4