A true sylvari should have two hearts: one soft and pliable as hot wax, and the other as hard and impenetrable as an icy diamond. The first, he should show to his companions, the second, to his enemy. Woe to the one for whom the two are the same.
The Nightmare Court is a home to those sylvari who reject the Ventari Tablet's teachings, embrace the nightmares encountered within the Dream of Dreams, and are attempting to understand them, while giving life to them with acts of evil. The primary goal of the Nightmare Court is to corrupt the Pale Tree herself, bringing her around to their twisted ideals so that the sylvari may be freed from the shackles of Ventari's Tablet and replace this philosophy of a centaur and a human by one which is uniquely sylvari.
The Nightmare Court do not consider themselves "perverse" or "evil." However, once within the court, their converts are forced to commit dreadful acts that destroy every last ounce of virtue they may have left. To achieve this, the Nightmare Court holds Dark Vigils, which consist of depraved tournaments and other detestable acts, all the while contributing to the growing Nightmare within the Dream. Nightmare Courtiers also have Dark Hunts, as opposed to Wyld Hunts, which they view to be their purpose for expanding the Nightmare.
The sylvari in the Nightmare Court do not unanimously share the same mentality. Some courtiers preach their way is about balancing the Dream and the Nightmare, and only convert those willing to join; others seek for the Nightmare to overcome the Dream and will forcefully convert others to their cause. In the end, however, all converts believe the Nightmare's path is correct, even if forced upon them, and are all more than willing to convince other sylvari to choose the same path, regardless of how they go about it.
The main portion of the Nightmare Court holds an apprenticeship system where low-ranking members are made servant to higher-ranking members. Members gain ranks as they become able to spread nightmare to others on their own, where they become a Knight and often take on titles, such as Knight of Decay, to help spread the nightmare. The highest ranks within the Nightmare Court are known as the Retinue, elevated to such a position by the leader and given new ranks: baron, count, countess, duke, and duchess.
There are, however, multiple splinter factions within the Nightmare Court and not all of these factions use the same structure and rank names as the Nightmare Court proper. Two splinter groups are known to exist: the Nightmare Court within Sparkfly Fen and Mount Maelstrom, and those who joined the Toxic Alliance.
The Nightmare Court was founded by the Secondborn Cadeyrn after a number of events, such as Niamh's refusal to dispatch of krait younglings and the refusal of the Firstborn to seek revenge on the asura for their treatment of Malomedies, convinced him that the Ventari Tablet was holding the sylvari back and that if the sylvari were truly to defeat the Elder Dragons, they would have to use any means necessary. It was Caithe's own statement that the Pale Tree would not listen to Cadeyrn, saying "You are either firstborn…or you are simply sylvari" that led Cadeyrn to create the Nightmare Court and forcefully make the Pale Tree listen to his views - an act Caithe later regretted.
Eventually, Cadeyrn had managed to bring the Firstborn Faolain into his fold, though this was after Faolain had first touched the Nightmare herself, and she later replaced him as leader, titling herself the Grand Duchess. Since then, Faolain has attempted multiple times to bring Caithe into the Nightmare. Caithe, believing herself responsible, traveled to the Nightmare Court base Twilight Arbor to put an end to a string of recent sylvari kidnappings by defeating the Nightmare Court. She was able to defeat Faolain, who fled, leaving Twilight Arbor abandoned by the Nightmare Court.
However, within Twilight Arbor Faolain had been growing a Nightmare Tree, which when grown is supposedly capable of granting others' desires of nightmare. As sylvari under Warden protection attempted to rebuild Twilight Arbor, the courtiers Fyonna, Leurent, and Vevina had arrived, causing panic among the non-courtiers, and competed fiercely for control of the Nightmare Tree.
In 1326 AE, some Nightmare Courtier groups had worked out a deal with Scarlet Briar, allowing the Aetherblades to set up a base within Twilight Arbor. What the Court gained from this deal is not yet known, however a splinter group (unknown if the same as those who let her into Twilight Arbor) has joined an alliance with the krait to form the Toxic Alliance.
 Concept art
Art by Kekai Kotaki.
- It has been stated that the Nightmare Court consists of approximately 10 to 15 percent of the Sylvari population.[verification requested]
- The concept for the Nightmare Court was derived from the Unseelie Court of Scottish folklore and other dark faerie lore.