[This chapter serves as a compendium of knowledge about the world of the novel. The information is gradually revealed within the story and is duplicated here for ease of access. As such, it may contain minor spoilers.]

- General Information:

❖ The Nightmare Spell

The Nightmare Spell infects young people, usually around sixteen to eighteen years old. After being infected, those chosen by the Spell experience an overwhelming desire to sleep. Once they succumb to this feeling, they are transported to the First Nightmare.

❖ The Nightmares

The Nightmares are trials created by the Spell. They are populated by both monsters and humans, which are considered to be illusory. Each Nightmare contains a central conflict that has to be resolved for the Nightmare to end. These conflicts are believed to be reconstructions of events from the ancient history of the Dream Realm.

❖ The Dream Realm

The Dream Realm is a vast, ruined magical world populated by Nightmare Creatures. It is also the place where Nightmares are born. Humans are brought there by the Spell after surviving their first trial and can only return to the real world through one of the special portals, which are known as Gateways. By accomplishing this feat, they become Awakened.

❖ The Awakened

The Awakened are people who have passed the first trial of the Nightmare Spell and established a connection with the Dream Realm. Each of them possesses special powers and a way to enter the Dream Realm to seek out and destroy Nightmares before they create a Gate, thus protecting the real world.

❖ The Gates

If a Seed of Nightmare isn't found and destroyed before it matures, a Gate from the Dream Realm is opened and a horde of Nightmare Creatures is unleashed into the real world. To destroy the Seed, any number of Awakened can enter the Nightmare and attempt to conquer it.

Thus, it won't be wrong to say that the duty of all Awakened is to enter the Dream Realm, seek out maturing Nightmares and close them before any harm befalls the real world.

- Common Terminology:

❖ Gateway

Not to be confused with a Gate, a Gateway is a special portal that serves both as an anchor for Awakened entering the Dream Realm and as an exit point for those wishing to leave it.

❖ Citadel

A human fortress in the Dream Realm built around a conquered Gateway.

❖ Memory

A magical item tied to the essence of a Dream Realm inhabitant. Memories are created from Soul Essence, but can assume physical form when summoned.

❖ Enchantment

A magical quality of a Memory.

❖ Echo

A magical copy of a slain Nightmare Creature. Echoes are capable of limited autonomy, but do not possess a soul, and thus are not alive. Just like Memories, they are created from Soul Essence and assume physical form only when summoned.

❖ Soul Core

A mystical core of one's spirit that is capable of accumulating and storing vast amounts of Soul Essence.

❖ Soul Shard

A physical manifestation of a broken Soul Core that contains remnant Soul Essence.

❖ Soul Essence

A mystical spirit energy.

❖ Soul Rank

A measure of power that is based on the quality of one's Soul Core. There are seven Soul Ranks:

● Dormant

● Awakened

● Ascended

● Transcendent

● Supreme

● Sacred

● Divine

Just like humans ascend toward divinity, Nightmare Creatures descend toward profanity. Their corrupted Soul Cores also have seven Ranks of power:

● Dormant

● Awakened

● Fallen

● Corrupted

● Great

● Cursed

● Unholy

❖ Class

A measure of power that is based on the quantity of one's Soul Cores. Unlike humans, who can only ever possess one Soul Core, Nightmare Creatures can possess many. This is another measurement of their power, called a Class. There are seven Classes of Nightmare Creatures, ranging from having one Soul Core to having seven:

● Beast

● Monster

● Demon

● Devil

● Tyrant

● Terror

● Titan

So, a Nightmare Creature with five Soul Cores of the Awakened Rank would be called an Awakened Tyrant, while one with four Soul Cores of the Fallen Rank would be called a Fallen Devil.

❖ Tier

A rough estimate of a Memory's potency that is based on its source. Although Memories follow the same Soul Rank hierarchy, they are also divided into Tiers based on the Classes of the Nightmare Creatures that left them behind. So, a Memory of an Awakened Tyrant (who possessed five Soul Cores) would be categorized as a Tier-Five Awakened Memory, while a Memory of a Fallen Devil (who possessed four Soul Cores) would be categorized as a Tier-Four Ascended Memory.

- Aspects and Abilities:

❖ Aspect

A confluence of one's innate affinities and choices manifested as a magical specialization. Aspects grant the Awakened unique powers, but also curse them with a Flaw.

❖ Attribute

A passive ability corresponding to one's natural traits.

❖ Aspect Ability

A magical ability tied to one's Aspect.

❖ Flaw

A unique curse placed on the Awakened as the price for gaining mystical powers.

❖ True Name

A mystical title granted by the Spell to the most exceptional of the Awakened.

❖ Hierarchy

The first four Soul Ranks, when applied to humans, have colloquial names in human language: Sleeper (Dormant), Awakened (Awakened), Master (Ascended), and Saint (Transcended). The word "Awakened" is also sometimes used to describe all carriers of the Nightmare Spell as a whole.

Sleepers are the carriers of the Nightmare Spell who have passed the First Nightmare. They receive the ability to perceive and interact with Soul Cores, as well as a unique Aspect and Flaw. Sleepers have no connection to the Dream Realm, but are destined to be transported there on the day of the winter solstice.

Once a Sleeper returns from the Dream Realm for the first time, they become an Awakened. Their Soul Core evolves to the next Rank and their Aspect gains a second Aspect Ability. They also become capable of perceiving and interacting with Soul Essence. Awakened enter the Dream Realm every time they fall asleep, appearing near the Gateway to which they are anchored.

If an Awakened chooses to challenge the Second Nightmare and succeeds, they become a Master. Their Soul Core evolves to the Ascended Rank and their Aspect gains a third Aspect Ability. Masters are capable of traveling between the real world and the Dream Realm physically, and not just in spirit. They only enter the Dream Realm when they choose to do so.

If a Master conquers the Third Nightmare, they become a Saint. Their Soul Core evolves to the Transcended Rank and they gain a Transformation Aspect Ability. There are only several dozen Saints in all of humanity.