The Door of Lust first appears on page 0768 where Ava Ire pulls up a sleeping Maggie's shirt to reveal the door, only to be mocked by Odin Arrow. Similar to the Drawer of Wrath, it can be used to transport physical objects between the real world, and the host's mind.
Maggie uses the Door of Lust to bring Gil's TITAN handbook into her mind for Tuls to use. After obtaining the blue rose from Tuls and waking up, Maggie re-opens the Door with the rose and handbook in the real world. The blue rose currently resides inside the Door of Lust. Additionally, there was a photograph of Maggie and Ava as children nailed to the door, which may suggest Maggie still cares about Ava subconsciously.