Faust

Faust (究明之王) was the Ultimate Skill of Veldora Tempest which evolved from his Unique Skill Investigator. He obtained Faust shortly before being released from the Infinity Prison. Raphael had demanded that Veldora obtain an Ultimate Skill so that he could be more useful to Rimuru, to which Veldora obeyed. In order to hide the fact that he was pressured by Raphael and as a way to surprise Rimuru, Veldora pretended that he didn't gain the Ultimate Skill himself but instead used the Gifts from Rimuru's Harvest Festival as an excuse for the origin of his Skill's evolution.

Abilities
Its essence is to reach the ultimate truth.

Sub-Skills

 * Thought Acceleration (思考加速): Accelerates the thought processing speed of the user.
 * Analytical Appraisal (解析鑑定): Analyzes and assesses the target.
 * All of Creation (森羅万象): The ability to comprehend any non-concealed phenomena in this world.
 * Probability Manipulation (確率操作): Allows the user to manipulate the probability of any outcome as they please. Against lesser targets and casual events it can manipulate the exact outcome that the user desires with complete accuracy but against targets of similar strength of will/existence it can only double the odds of a specific outcome.
 * Pursuit of Truth (真理之究明): Allows the user to access the records of the world's events.
 * Risk Prediction (危険予知)

Trivia

 * This Skill is named after, the protagonist of a German legend, a scholar on a quest for knowledge who made a pact with the Demon.
 * Incidentally, Veldora's disciple, Zegion, eventually awakened the Ultimate Skill Mephisto, which is named after Mephistopheles.