Qadesh's Heart Chamber takes the shape of a pulsing heart constructed from brown flames. It can combine with Qadesh's Blood Seal and Qadesh's Blood Pulse to form the Rubble Giant, with the Heart Chamber acting as the Giant's cockpit and reactor.
By using Heart Chamber with Blood Seal, Khamsin can conduct Tuning. A mental image of the location's "original form" is needed to conduct Tuning, so a local human is put inside Qadesh's Heart Chamber. Qadesh's Blood Seal markings are placed around the location to be tuned, with Heart Chamber at the center of the markings like a relay point. A flow of Power of Existence to the Heart Chamber is harmonized, and the human's image of the harmony they feel, which is a new image of the location using their old one as base, is projected and harvested. Heart Chamber then resonates with the Blood Seals around the location as an Unrestricted Spell Insignia in order to complete the Tuning.
Having Qadesh's Heart Chamber as a relay point for the Blood Seals and harvesting the mental images is the opposite of its original use of controlling Blood Seal, so sometimes Khamsin and Behemoth's emotions and minds flow through the flames.
It can also cover an individual, protecting them.
- Qadesh's Heart Chamber, along with Blood Seal and Blood Pulse, are named after the Canaanite and ancient Egyptian fertility goddess Qadesh.
- For some reason, humans who enter Qadesh's Heart Chamber become naked. It is unknown in the novels whether the Flame Haze Khamsin would also become naked. In Volume XVIII Khamsin talked to Shana and the others inside the unobstructed Heart Chamber, but they didn't show any reaction to this. In Volume XX, an illustration depicted Khamsin's upper body bare, but there were similar illustrations for Margery Daw inside Tōga and Wilhelmina Carmel, so it might simply be because Noizi Itō wanted to depict him that way. In the derivative work Prison of Destruction, Khamsin stated that he was also naked within Heart Chamber. The image of Yoshida naked while using Heart Chamber in Volume VI predated the first mentioning of that effect of Heart Chamber in Volume VII, so Yashichirō Takahashi may have been influenced by the illustration.
- The anime depicts the Tuning spell causing Yoshida to be naked when conducting the Tuning but the Heart Chamber wasn't present. It also depicts Khamsin fully naked within Heart Chamber.