Tree of Names

The Tree of Names is a tree sacred to the Gau Drashari and important to the Pact of Crown and Throne to which Avalir is beholden. It writes a protective spell against extraplaner threats across the face of Exandria while Avalir travels the leylines, though this purpose is kept secret from the city's wizards out of fear that they may use this for personal gain.

Since the Replenishment following the ascension of the Raven Queen, 119 years prior to the events of Exandria Unlimited: Calamity, it has been protected by a piece of arcane equipment known as the Arboreal Calix.

Description
The Tree of Names is a beautiful blossoming tree with dark wood and dark leaves located in the Meridian Labyrinth of Avalir. It hovers in the center of the Arboreal Calix, a stone chamber created to protect it. It is connected to other Planes of Existence simultaneously, possibly growing straight through the leylines of the planes; Loquatius Seelie smells the Feywild when standing near it and surmises that "maybe nothing's very far from here". The Tree of Names captures anything moving into Exandria from another Plane of Existence, such as Evandrin and a model of Avalir when they returned from Celestial Plane. It is capable of defending itself when it is touched or when its secrets are at risk: it grows quickly around whoever is touching it and can attack those nearby with its branches.

It seemed to have additional protective properties against some extraplanar entities already on Exandria, as fiends seen in Avalir would vomit blood and blossoms. It is indicated to have a connection to the Ritual of Seeding.

Arboreal Calix
The Arboreal Calix was installed over the Tree of Names to protect it, shortly after the Raven Queen ascended, by the druids of Toramunda. Since then, "Arboreal Calix" has supplanted the Tree of Names as the term people use.

While Laerryn is unaware of what the machinery does, she is aware that over half of the raw magic energy required as a tithe per the Drashari Pact goes solely to the Arboreal Calix. After Laerryn successfully transported the model of Avalir to another plane, she found that the Arboreal Calix drew noticeably more magic.

Background
The Tree of Names was created by the druids of the Gau Drashari to sit in Avalir when it was first lifted 292 years before the events of Exandria Unlimited: Calamity. Because Imyr Por'co and his fellow wizards intended to fly along the leylines of Exandria, the Gau Drashari made the tree to write the runes of a protection spell against extraplanar threats, specifically by writing "the names of those things beyond which should not come" as it dropped blossoms across the world. The leader of the Gau Drashari did not trust the wizards would protect the tree if they knew its true purpose and would instead use its power for personal gain, so the Gau Drashari refused to tell the people of Avalir what the tree was truly doing.

It became a key artifact of the city, one that is "incredibly, profoundly important to the significance and safety of Avalir", and the Eyes of Avalir were tasked with forever protecting it. Members of the Eyes are instructed that mere mention of it was an indication that something terrible was possibly about to happen.

Exandria Unlimited: Calamity
While investigating Vespin Chloras, Cerrit Agrupnin, Senior Sightwarden of the Eyes of Avalir, discovered an old recording in the archives of the Herald's Tome where Vespin mentioned the Tree of Names to Loras as something that Loras did not know about. Cerrit remembered what the Eyes of Avalir are told about the significant of the tree and relayed this to the rest of the Ring of Brass about this. Zerxus mentioned that there had been a tree in his earlier dream, held in the palm of a Betrayer God, and that the blossoms of the tree fell on Evandrin. He felt this related to Evandrin's disappearance.

In, most of the Ring of Brass went to the Tree of Names to investigate it further. When they did so, they found that objects sent across the planes were caught in its branches. This included Evandrin, who was sent across the planes by Laerryn Coramar-Seelie years ago as a test for the Astral Leywright. Patia Por'co attempted to learn more about it, and in doing so learned its true purpose. Loquatius Seelie tried to pull Patia away from the tree, which was growing around arm, and saw into the Feywild. Lady Elmenore, noticing this, told him that he must prevent Patia from finding the names.

Laerryn cast Blight on the tree, breaking it in two, after the tree hurt Patia and Loquatius to defend itself from Patia trying to learn its secrets. Vespin then emerged from it, followed by Asmodeus.

Trivia

 * In Latin, "calix" means "chalice" and is derived from the Ancient Greek "κύλιξ" (kylix). So, together "Arboreal Calix" indicates a tree-like chalice, or a chalice for a tree. Additionally, in botany, the calyx is a cup-shaped group of leaf-like sepals at the base of a flower. This is derived from the Latin "calyx", which in turn is derived from the Ancient Greek "κάλυξ" (kálux); "calix" and "calyx" are distinct words in Latin, though they are used interchangeably in botanical Latin.