Fate/Kaleid/Einzbern family

The Einzbern family is a family of homunculi that are, for the most part, indistinguishable from normal humans. About the only real differences between the Einzberns and normal humans are the extraordinary levels of magical power they possess, and the fact that they are all female. They even reproduce in a manner rather similar to that of humans, using sperm and mana taken from a human male, who they prefer to be a mage of some power, to create their daughters. (Daughters born to the Einzbern family always take on the family name, not the father's name.)

The magic used by the Einzberns is to create magical filigree constructs, using magically created wires to form shapes witch can be commanded to move as the caster wishes. Constructs made from these filigrees of magical wires will be incredibly dense and sturdy despite their delicate looking design, and can move with speed and momentum that defies logic if the caster is in active control over them. If they are formed into an animal-like design, they can also act autonomously from the caster. They will move as the animal they are constructed to resemble, but will have the intelligence to perform a simple task that was given to them by their caster such as "search," "attack," "guard," or "dig a hole."

The most powerful magic that the Einzbern family possesses though is knowledge of the ritual to summon the Holy Grail. This magic involves imprinting the knowledge of magic held by the grail into one of their unborn daughters still in the womb. That daughter will then harbor the power of the grail until it unleashes, at witch point she will become a key that completes the holy grail ritual at its end, sacrificing her in the process. She is not the only sacrifice however. 6 of the 7 heroic spirits also have to be sacrificed in a mock war as well, leaving the mage who summoned the 7th to acquire the grail at the end. The Einzbern family wishes to obtain the grain and thus participates in every Holy Grail war, but due to the nature of the ritual they are required to let in 6 other random mages as chosen by the magic of the grail itself.