It had evolved from Unique Skill Sage during his death, as he thought that since he was approaching his forties as a virgin, he must be something much greater than a mere wizard.
Great Sage has a heartless and emotionless personality and is solely driven by purely logical computations. It cares for nobody but the benefit of its master, Rimuru.
Auto Battle Mode: By giving permission to Great Sage, one can let it control his or her body temporarily.
Initially, Great Sage could only respond in a fashion where it asked Satoru Mikami [YES/NO] questions about activating his skills. It could not converse further than that.
According to Great Sage, after Satoru's soul had settled in the Slime body, it needed 90 days to "establish" itself. Till then, it was accessing and usurping the Voice of the World. Thus, for quickly utilizing Satoru's skills, a response function was added, and it could answer any of his questions in properly structured sentences. Normally, a convenient skill that answers any questions doesn't exist. So, to answer his questions, it was trying to find a way to attain that particular function. Although it was finally able to answer questions, it remained passive and lacked ego: it wouldn't answer unless asked.
After knowing about "Chant Annulment" and "All of Creation," Satoru linked the ability of Predator's "Analysis" and Great Sage's "Parallel Processing" to improve analytical capability. As an experiment, he first tried out the new ability to scan the Hipokte Grass he had been 'eating' for 90 days. Establishing the link made analysis take 1 second and production of restorative items 3 seconds. Without the link, it takes 50 minutes.
- Thought: Raises thought-processing speed a thousand times.
- Analysis and Judgment: The ability to analyze and make judgments regarding a target.
- Parallel Processing: The ability to detach thoughts and analysis of phenomena.
- Chant annulment: When using magic, the chant is no longer necessary.
- All of Creation: The ability to comprehend any non-concealed phenomenon in this world. Depending on the things the user understands and the information the user knows about, additional information can be inferred. In other words, the user needs to see it (the phenomenon) at least once.