The Seven Legacies
The Otherworld is made up of 7 world, starting from the Red Zone and ending with the Purple Zone.
Each Zone has a legacy that was left behind by the fallen races.
Kang Hansoo's goal is to obtain their legacy in order to strengthen Humanity.
Red Zone - World Tree
A depiction of the World Tree.
The Elvenheim, the past natives of the Red Zone, created the Divine Stone and <World Tree> and unified their entire race. The Divine Stone powers the World Tree. The branches and leaves allows for teleportation. The fruits stimulates growth hormones and greatly shortens the time needed to reach adulthood. The roots sucks up toxic water, purifies it, and supplies endless nutritional fluids to eat.
Only one race can receive the protection of the <World Tree> at a time. Once a race starts receiving the protection of the <World Tree>, all other races will be treated as foreign objects and get thrown out into the void by the <World Tree>. Tekilon, an Akaron who transported his soul into the body of the future Elvenheim King, created the Five Calamities to weaken the <World Tree> and to destroy or exile the Elvenheims in order to monopolize the protection for his race living in the Orange Zone.
The <World Tree> was revived by Kang Hansoo and has granted protection to the Human Race. The Red Zone becomes the <Barracks> to provide a "new Earth" and prepare incoming humans, while training and multiplying existing ones. The <Barracks> purpose is to create an end result of billions of soldiers.
Orange Zone - Body Enhancement Surgery
The Akarons, the natives of the Orange Zone, created the <Body Enhancement Surgery> and unified their entire race. The surgery is genetic engineering that uses the genes of the Gragos, creatures that are able to bathe in and drink lava, to strengthen stamina, enhance a person's body, increase their longevity, lessen the amount they need to eat, and increase one's battle powers by a huge amount.
A depiction of the Body Enhancement Surgery.
The surgery pulls the essence from the body of the Gragos and integrates it into one's body. The person undergoing the surgery is submerged in a tank of silver liquid metal that changes one's entire body step by step. Protein-based muscle is replaced with liquid-metal-based muscle. The surgery has the option of increasing one's height and muscle appearance. It is not something anyone can receive however. Receiving the surgery is only possible if one has the physical basis that can support it, else their body will blow up.
If a person emerges before the surgery is completed, the body will activate the defense system and attack the unsettled liquid metal within one's body. This cases excruciating pain.
The surgery provides the user powerful strength and limitless stamina but this is all secondary. The primary purpose of the surgery is the regeneration boost that allows one to heal even fatal injuries, just as long as the person is still alive. The silver liquid that runs around one's body allows one to regenerate at a rate tens of times faster than normal. The silver liquid metal can reattach missing limbs and even knit up a person's lower half if it is cut off - as long as the person can pull himself together quickly enough.
Humanity gains access to the <Body Enhancement Surgery> from the Akarons in the Orange Zone. With this surgery, humans can gain a body that can survive the dangerous environments that exist in the Abyss without wasting mana on skills to combat the elements.
Yellow Zone - Mana Pool Surgery
The Sages, the natives of the Yellow Zone, created the <Mana Pool Surgery>. This surgery creates and places an organ called <Mana Pool> into the body of a person which gives the person an amount of mana "as large as the oceans". It allows the person to use mana "non-stop like monsters for days", and increase the original mana capacity by a few times more. The Satellite Fortresses have a system inside its body that can implant the <Mana Pool>.
A depiction of the Mana Pool organ circulating mana around the body.
The requirement to receive this surgery is to have a body similar to the Sages. Humans have a similar body to the Sages so humans are able to receive the surgery without any issue.
Hansoo received the Mana Jade instead of a <Mana Pool Surgery>, which were both created by Karmen, the ex-king of the Sages. Where a Mana Pool is like a pool-like system, the Mana Jade works like a small mana-engine version of the satellite fortresses.
Green Zone - Ain's Blessing and Spirits
The Ains, the natives of the Green Zone, can give people their Blessings. Those who have killed an Ain will receive a curse mark which will make it impossible for the person to acquire an Ain's Blessing. When a person receives the blessing, a shining symbol appears on their chest. The blessing has one purpose: Being able to partly control the ability of the Ains, those who were born with the right to control the spirits and elements. But the blessing only allows the user the right to use the strength. Without a spirit to control, its abilities are limited.
After one has received the Ain's Blessing, they can obtain the Spirit's power. The Ain's Blessing is like an empty house that needs an existence, a Spirit, to fill it up. The blessing allows one to control the tremendous amount of strength the spirits contained. Without the blessing's protection, ones body would get destroyed and melt from the power of the spirits. The blessing will point towards the direction in which one will be able to find a spirit. It can also protect the user from the environment by having the blessing persuade the environment to not attack the user. There is a limit to the blessing however.
The spirit is something that is as powerful as a Mana Jade. The level of the spirit one gained was relative to one's strength and quality of the blessing. When obtaining a Spirit, the Spirit enters the user's consciousness and merges with it. Only by taming the Spirit will one be able to use its powers. The user can either make an agreement with the Spirit or forcefully make it submit by defeating it in battle. If the user loses, the soul can take over the user's body by force. The defeated soul can not deny the orders of a soul at a higher station. The spirit cannot be used fully if the spirit does not like the user or if the spirit is not compatible with the user. Only after resonating through a long period of sharing their souls together would they be able to let out more powerful might.
One can also go through Fusion, a battle for ownership with their soul and mind at stake. It is a battle between souls to determine who was more suitable for the body. Whoever wins, the other's soul and mind will disappear forever. If the user wins, all the powers of the Spirit will belong to them. Through fusion, a person can obtain a body made for the spirit and wield its power fully. During the fusion process, one goes through the memories of the other. The first to tire loses.
The Spirit allows for perfect acclimation to the surrounding environment as well as the power to prepare for any unknown variables and to control vast amounts of energy. It can protect the person from the environment as well as wield the mana in the area. It can divert a fraction of the energy from the enemy's attack and use it for itself. This allows one to reduce the power of the enemy and increase one's own defenses.
Humanity received the Ain's Blessing after making an alliances with the Ains after freeing them.