Ultimate Skill

Ultimate Skill (究極能力) is the evolved form of Unique Skill and the final evolutionary stage of Skills in general.

Characteristics
Ultimate skills, as the name implies, gives the wielder ultimate power to control the very laws of nature. The only way to counter an ultimate skill is with another ultimate skill. That is the absolute, unbendable rule of the world.

If unique skills are born from one's individuality, ultimate skills are born when unique skills are brought past their limit. That's why no ultimate skill is identical.

As the story progresses, it's revealed that through certain methods, ultimate abilities can be imparted to those who have not naturally awakened them. The only requirement, like natural ultimate skills, is that the recipient must be awakened to qualify for it.

Angelic System
Angelic System (天使系) are a family of ultimate skills directly created by Veldanava, each bearing the name of angels. Among them, the most powerful are the Virtues (美徳系), seven skills born from isolating Veldanava's divine authority over creation. After the world stabilized, he divvied them to those he considered worthy, keeping Michael for himself, and released the rest into the wheel of reincarnation to choose their own masters. As they were too powerful, they were restricted to the unique skill level.

All the ultimate skills of the angelic system are linked to Michael with narrows corridors directly built into them during their conception, making their holders subject to the absolute control of Michael.

Demonic System
Demonic System (悪魔系) are ultimate skills born as counterparts to the angelic system. Among them the most powerful are the Deadly Sins (大罪系), seven skills corresponding to a person's fundamental desires. Though born as imitations of the angelic system, demonic skills boast the same potency as their angelic counterpart. Demonic skills, like their Angelic counterparts, also tend to choose their masters, sprouting within them as degraded unique skills.

Ultimate Skills
Rimuru Tempest:
 * Azathoth, God of Void
 * Shub-Niggurath, Lord of Abundance
 * Raphael, Lord of Wisdom (formerly)
 * Beelzebuth, Lord of Gluttony (formerly)
 * Veldora, Lord of Storms (formerly)
 * Uriel, Lord of Vows (formerly)
 * Velgrynd, Lord of Scorch (formerly)

Veldora Tempest:
 * Nyarlathotep, Lord of Chaos
 * Faust, Lord of Investigation (formerly)

Diablo: Zegion:
 * Azazel, Lord of Temptation
 * Mephisto, Lord of Illusion

Benimaru:
 * Amaterasu, Lord of Shimmering Flame

Testarossa:
 * Belial, Lord of Underworld

Ultima:
 * Samael, Lord of Deathly Poison

Carrera:
 * Abaddon, Lord of Destruction
 * Sandalphon, Lord of Judgement (formerly)

Ranga:
 * Hastur, Lord of Starwind

Beretta:
 * Deux Ex Machina, Lord of Machine God

Luminous Valentine:
 * Asmodeus, Lord of Lust

Hinata Sakaguchi:
 * Fortuna, Lord of Odds

Yuuki Kagurazaka:
 * Mammon, Lord of Greed

Vega:
 * Azi Dahaka, Lord of Evil Dragons

Chloe Aubert:
 * Sariel, Lord of Hope
 * Yog-Sothoth, Lord of Space-Time

Velzard:
 * Gabriel, Lord of Patience

Velgrynd:
 * Cthugha, Lord of Flame God
 * Raguel, Lord of Charity (formerly)

Milim Nava:
 * Satanael, Lord of Wrath

Dino:
 * Belphegor, Lord of Sloth
 * Astarte, Lord of Heaven

Masayuki Rudra Nam Ul Nasca:
 * True Hero, Lord of Heroes
 * Uriel, Lord of Vows (through True Hero)
 * Michael, Lord of Justice (through True Hero)

Guy Crimson:
 * Lucifer, Lord of Pride

Leon Cromwell:
 * Surya, Lord of Brilliance
 * Metatron, Lord of Purity (formerly)

Zalario:
 * Metis, Lord of Sanction
 * Israfel, Lord of Judgment (formerly)

Obera:
 * Azrael, Lord of Salvation (formerly)

Pico:
 * Jibril, Lord of Rigor

Gracia:
 * Haniel, Lord of Glory

Ultimate Enchantments
Single Digits:
 * Alternative

Yuuki Kagurazaka:
 * Melchizedek, Lord of Dominion

Arios:
 * Sandalphon, Lord of Punishment

Orlia:
 * Multiple Weapons, Lord of Martial Creation

Mai Furuki:
 * World Map, Lord of Topography

Jahil:
 * Agni, Lord of Blaze

Vega:
 * Multiple Weapons, Lord of Martial Creation

Kagali:
 * Agastya, Book of Prophecy
 * Melchizedek, Lord of Dominion (formerly)

Tear:
 * Orpheus, Optimistic Player

Ultimate Gifts
Souei:
 * Tsukuyomi, Lord of Moonshade

Gabiru:
 * Mood Maker, Lord of Psychology

Geld:
 * Beelzebub, Lord of Gourmet

Kumara:
 * Bahamut, Lord of Mythical Beasts

Apito:
 * Proserpina, Queen Possession

Adalman:
 * Necronomicon, Book of Magic

Albert:
 * Immortal

Venti:
 * Eternal

Gadra:
 * Grimoire, Book of Magic

Veyron:
 * Artist, Authentic Writer

Agera:
 * Blade Transformation

Trivia

 * In the story, the characters pronounce Ultimate Skills using only the being they reference and not the entire names used in the wiki and translations. Meaning, it's "Ultimate Skill Beelzebuth" not "Ultimate Skill Lord of Gluttony Beelzebuth." This is due to the Japanese texts themselves. (See: Furigana and Ruby Characters)