The Dreamflower is the Great Existence that controls the Tide of Ashes. Stargazer says that it came from "the Realm of Truth" and that it is responsible for awakening her as a Sinner. It is an enormous alien organism composed numerous tangled vines beneath a crown that resembles both a blooming flower and a humanoid face. Despite its plantlike appearance, the Dreamflower is conscious and intelligent. In addition to its mastery over the Tide of Ashes, it also has prodigious mental powers, able to both spread Mania like other Great Existences and to dominate the minds of humans and animals alike.
There is evidence that the Dreamflower may predate the Nightfall era, as it was discovered beneath the ruins of an ancient palace in the deep desert. Murals in the ruins depict humans worshipping a fiery entity that descended from the sky and took the form of a flower. Nevertheless, in the modern era, the few WhiteSands residents who are aware of its existence fear it as the source of the calamity, and call it the Filthflower.
Ash Crystals
The Dreamflower's body also includes the mineral components called Ash Crystals, which are referred to as the creature's three hearts. These grey prismatic crystals give their holders the ability to borrow the Dreamflower's power to exert control over the Tide of Ashes and desert sandworms. According to Stargazer, the Dreamflower gave out its three hearts in order to understand humanity. The first Ash Crystal was "bestowed upon a brave soul who dreamed of traveling WhiteSands" and was eventually acquired by EDGE and then given to the MBCC for study; the history of this Ash Crystal is almost entirely unknown. The second Ash Crystal was given to Stargazer when she became a Sinner, and replaced her heart. The third Ash Crystal was stolen from the Dreamflower by bandits, who used it to attack cross-desert shipping from DisCity.
When the three Ash Crystals were returned to the Dreamflower during the Raging Sands event, it gained enough strength to break the constraints placed upon it by the Usum Experiment. With this power, it intended to direct the Tide of Ashes to destroy DisCity, having been convinced through the Crystals' observation of humanity that they weren't worthy of its gifts. However, the Chief is able to convince it that Stargazer had not truly given up on humanity, and it instead returned to the "Realm of Truth" alone.
Usum Experiment
At some unknown point in the past, the Dreamflower was the subject of extensive research known as the Usum Experiment. The operators, goals, and methods of the Usum Experiment are not known, but in the remains of their laboratory, the Chief finds the same vertical eye insignia used by the Underground. The researchers' notes describe how many humans subjected to the Dreamflower suffer from severe Mania and ultimately become Corruptors, but they do not seem to have exact terminology for these phenomena, suggesting that the research took place very shortly or even before Nightfall.
The researchers experimented with the Dreamflower's effects on various living organisms, beginning with small sandworms, which rapidly mutated into the enormous monstrosities that prowl WhiteSands in the present day. They also experimented on humans, and found that while roughly two-thirds of those subjected to the Dreamflower contracted Mania, died, and became Corruptors, the remaining one-third became "spiritually devoted" to the Dreamflower instead. It was determined that the Dreamflower possessed "higher dimension" consciousness and the ability "place rules" over these subjects, as well as over the mutant sandworms, effectively controlling their minds and actions.
After 44 days of experimentation, Usum researchers encountered massive monsters surrounding the site, possibly the first appearance of the Apostles of Ash. The following day, as the Apostles approached the site, the researchers began a "ceremony" which confined the Dreamflower's roots with "shackles of light". These researchers' exact relationship to the Shackles is unknown.