It remains unclear as to who created it, and why Death was kept there in the first place. However, the Heavenly Host held some knowledge of his trappings. As they knew where it's location was as well as how to open and seal it, being as they have in the past raised Death for certain occasions. One of which occasions being the Deluge, more commonly referred to as "Noah's Ark".
Lucifer, after completing the ritual, digs a ditch, and it rumbles as Death ascends up. When the Horseman's out, Lucifer greets him with, "Oh, hello, Death".