Celenike Icecolle Yggdmillennia

I'm sorry, Mr. Mashin1.
…One of the Masters of the “Black” Camp. She is a magus of cursing techniques who curses her enemies to death. She has great skill, but she fails in terms of personality. She also possesses abundant knowledge of the modern era and has even tried to curse people to death on the computer through the electronic network.
In the Icecolle family's dark arts rituals, it is the one that kills the sacrifice rather than the sacrifices themselves that must fall into a trance state. They always watch and deal with the other person with ice-cold eyes. It is the same as taking a solemn attitude towards the lives of living creatures when cooking meat.
It is the correct way to act when facing those who will become sacrifices—at the very least, the Icecolle family teaches this doctrine.
But still, perhaps they sacrificed too many people. Gradually, the thread of curses binding the Icecolle family became too thick and strong, and the additional factor of them moving their territory caused them to suddenly decline. Though the other members of the Icecolle family noticed Celenike's distortion, they chose to shut their eyes to her sadistic hobbies due to her rare talent.
That pampering became the underlying cause that led her to prioritize her personal desire in the midst of the Great Holy Grail War and meet a tragic end… Well, she serves as an example that shows how magi who mistake the objective of their training end up like this. Or perhaps the sacrifices that the Icecolle family had killed until then had aimed to balance accounts in this way.
There are two flaws to cursing someone. No matter how well you curse someone to death without exposing your actions—that curse will eventually rain down upon the curser on a whim. Celenike just happened to receive the backlash this time.

Fate/Apocrypha material: Fate/Apocrypha Encylopedia
Translator's Notes
  1. ^ This is the author of the manga Fate/school life. This is most likely referencing how Mashin is known to be a fan of Celenike and apologizing for how she died.