Also check out Sumer's quote on the summer Magic doll card.
Basically, Sumer created magic dolls (golems animated with human souls) as Maids for the wealthy of Crest (crest has a large nobility of varied families that don't necessarily get along). The original one is the Standard Magic Doll from Set 1, which, legend has it, was made by Sumer to look exactly like she does. She eventually started creating alternate versions for other tasks, and modifying them for battle.
Then, during the war of the Sun and Moon, a noblewoman named Belfyna became involved with Annarose, who ordered her to raise an army to go retrieve Mylfere. Belfyna had no army, but she had money, so she hired Sumer to begin making a series of specialized combat Magic Dolls. Now, Sumer had all the funds she needed to bring her research to a new level...
This story can be put together by the flavor text of all the cards mentioned above.
"Scissors are overpowered. Rock is fine." -Paper