Summary
From a simple skill that allowed him to change the shape of his body at will, to a skill that enabled him to devour anything he wants,Rimuru Tempest has acquired tons of skillsthat will help him not only in battle, but also in a day-to-day situation.
One of those skills is an ultimate skill called Raphael. Out of a wide array of skills within his disposal, Raphael is by far the one that he uses the most. What most people may not realize, however, is the fact that the Ultimate Skill Raphael is actually a lot more fascinating than you might think. So here are all the things that you need to know about this peculiar and overpowered skill.

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It Is Actually Rimuru’s Reincarnated Skill
In the world ofThat Time I Got Reincarnated as A Slime, every reincarnated person gets some sort of skills upon their arrival. The guild master Yuuki Kagurazaka, the hero Masayuki Honjou, andthe holy knight Hinata Sakazuki, just to name a few, are all bestowed with a unique skill when they are reincarnated to the new world. For Rimuru, that skill is known as the unique skill called Great Sage.
The Great Sage is one of a handful of skills that not only has a speech capability, but it also has an awareness. Granted it can only give limited responses and although it has some level of awareness, it hasn’t developed a fully functional consciousness yet. Think of it like the early version of an A.I. language model like ChatGPT. And just like ChatGPT, Rimuru can use the Great Sage to do all sorts of things for him. From navigating through the difficult terrain to maximizing the effectiveness of his other skills, the Great Sage is like a loyal assistant that canhelp Rimuru do everything he wants.

Furthermore, unlike other skills that can be activated or deactivated at will, the Great Sage is always on all the time. Interestingly enough, the Great Sage seems to consume little to no mana at all. Because despite always analyzing and giving proper support in the background, Rimuru never feels any adverse effect of a non-stop use of the Great Sage, which is another reason why this skill is so powerful and versatile.
From Unique Skill to Ultimate Skill
During the invasion attempt of the Kingdom of Falmuth, Rimuru single-handedly massacred more than 20,000 soldiers of the Kingdom. In doing so, he has fulfilled the necessary condition to level up to a much higher being. In this case,he can evolve into the first ever demon lord slime. The level up ritual is called the Harvest Festival.
During the procession, Rimuru lost his consciousness and was forcefully put to sleep for quite some time. After all, the level up ritual is akin to a caterpillar covering itself with a cocoon before eventually turning into a butterfly. The monsters that he has named also undergone a level up process as well. During the time when Rimuru lost his consciousness, the one who controls his body is actually his unique skill: The Great Sage. As a matter of fact, this sentient skill is the one who makes sure the Harvest Festival goes as smoothly as possible, both for Rimuru and his brethren.

Interestingly enough, Great Sage also uses this time to level up itself. Yes, this unique skill decided to level up along with its master. The reason is simply because as his master grows stronger, it too needs to improve in order to better serve the needs of its master. And that is how the skill that has been with Rimuru since the day he was reincarnated to this wonderful yet dangerous world, the Unique Skill: Great Sage, has finally evolved intothe Ultimate Skill: Raphael “Lord of Wisdom”.
One Skill To Rule Them All
As one of the most powerful individuals in the world, Rimuru has tons of skills.Some are absurdly powerful, like Beelzebuth, while others are useful for mundane stuff like creating a new set of wings on his back. Not to mention he also gains the ability to use his subordinate’s skills through something called the Soul Corridor. Not to mention he also has the ability to create new skills, such as the physics-based magic, Megiddo. This means Rimuru now has hundreds of skills at his disposal.
One thing worth noting, however, even thoughRimuru has become a Demon Lord with unparalleled powers, it is still impossible for him to remember every detail of his hundred different powers, and find the most effective and efficient way to use them, especially in the middle of an intense combat. And that’s where the Ultimate Skill Raphael “Lord of Wisdom” comes in. If the Unique Skill Great Sage is akin to an early version of ChatGPT, then the Ultimate Skill Raphael is similar to the advanced version of Jarvis, the all-knowing A.I. assistant from the Iron Man movies. After all, not only Raphael has gained a much better speech capability now, it also acquired a true consciousness.
And just like Jarvis, its main purpose is to serve its master as best as it could. That means managing every skill that Rimuru and his subordinate has, analyzing the opponents during a live combat situations and proposing the best course of actions, performing all kinds of behind the scene calculation that requires a tremendous amount of computational power, such as molding Rimuru’s mana tocreate complex magic formulain order to improve existing skill/attacks/defense or crafting an entirely new skill/magic altogether, just to name a few.
In the light novel, there are even instances when Raphael is tinkering with Rimuru’s subordinate’s skills through the soul corridor in order to make it so much more effective and efficient to use. So basically, Raphael is the reason why Rimuru can achieve so many extraordinary things that should be impossible for a regular living being.
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