Golem Keter Malkuth

Royal Crown, the Light of Wisdom. The Noble Phantasm of Caster of “Black,” Avicebron. It is not something that he created while he was alive; rather, it is his unfulfilled dream that was turned into a Noble Phantasm. It is an imitation of the “first human Adam,” a Reality Marble which has been given life of its own.
Just by stepping on the ground, it is endlessly supplied with mana, and at the same time it encroaches on the surrounding land and turns it into “Eden.”
Its full height was fifteen meters at the time of its birth, but this is only the measurement of “when it was born.” As the span of Eden expands, the giant's size will change and multiple, until it finally exceeds a thousand meters. It is said that “a fifteen-meter-sized giant could be easily defeated by even a Servant with average C rank stats, but as expected, one at the size of a thousand meters would be impossible to kill without a group of first-rate Servants. And, incidentally, the stomachs of the people tasked with covering up it all up would die.
The reason Jeanne and the others were so frantic against the giant when it was still fifteen meters tall is because they could tell that the speed of its growth was extraordinary, and if their response had been even a bit slower, the giant would have grown to thirty meters and displayed even harsher resistance.

Fate/Apocrypha material: Fate/Apocrypha Encylopedia