Board Thread:Dark Souls III/@comment-107.215.150.34-20160605053647/@comment-28362064-20160605072336

The doll is acquired after defeating the Deacons of the Deep boss in the Cathedral of the Deep past the Road of Sacrifices.

You still have to face the Sulyvahn's Beast on the bridge, but it cannot pass the barrier. If you choose not to fight him, he will respawn at a later portion of the area.

Hope this helps,

-HD