Tree of Qliphoth

The Tree of Qliphoth (クリフォトの樹) is a magic channel that connects to the underworld and allows devils to enter the living world. One of the Dark Triad's objectives is the recreation of this channel.

Overview
The ritual for opening this channel, known as the Qliphoth Advent Ritual (クリフォト降臨の儀), involves using World Tree Magic and Dark Magic to open seven gates on seven different levels and takes seven days. Once the final and lowest gate is opened, the World Tree and Dark Magic users will die. Ritual of the Advent is a large magic circle powered by four functions. One is the Site of the Advent of Qliphoth located in a center. The remaining three are for activators of the Ritual located in different perimeters of the circle. By defeating all activators, the ritual will be stopped.

Ten devils are set along the depth of the channel and are released as the gate to their level opens. The devils on the lower levels are stronger than the devils on the upper levels. The devil on the lowest level is Lucifero.

History
Within the inherited knowledge of the Heart Kingdom's princesses, Lolopechka finds memories of a previous opening of the channel and the devastation it caused. The resulting destruction would devastate the entire continent and result in the massacre of 90% of the human population, bringing humanity close to extinction.

The Dark Triad of the Spade Kingdom plan to recreate the channel, so Zenon Zogratis leads an attack on the Golden Dawn squad in order to capture William Vangeance, while Dante Zogratis attacks the Black Bull squad to capture Yami Sukehiro. The two captains are brought to the Spade Kingdom, imprisoned in coffins, and placed in the center of a series of magic circles.

Trivia

 * The Qliphoth is the arrangement of evil forces in Kabbalah and is the opposing structure to the Sefirot, which was used for the elves' apostles and the tree of life monument.
 * The structure also resembles the nine circles of Hell from Dante's Inferno. In the poem, Satan, or Lucifer, is imprisoned on the lowest level.
 * Tabata accidentally drew the underworld as having nine levels instead of the intended seven.