Growth

Is able to receive the blessing of the earth, so that as long as it's feet are on the earth, it cannot be destroyed with any means.
After it is born it's body doubles in one hour intervals, the largest size is approximately 1000 meters.

FAM 26-27


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.

FAM 166