Ultimate Skill

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

Ultimate Skill Characteristics
Ultimate skills, as the name implies, give 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.

Ultimate Skills
 Rimuru Tempest   Veldora Tempest   Ruminas Valentine 
 * Raphael, Lord of Wisdom
 * Beelzebuth, Lord of Gluttony
 * Veldora, Lord of the Storm
 * Uriel, Lord of Vow
 * Faust, Lord of Investigation
 * Asmodeus, Lord of Lust

 Yuuki Kagurazaki 
 * Greedy King Mammon

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 Gluttonous King Beelzebuth." This is due to the Japanese texts themselves. (See: Furigana and Ruby Characters)