That Time I Got Reincarnated As a Slimeis one of the more successful isekai series around, having not only a long-running light novel series but a popular manga series and an even more popular anime serieswith a third season on its way. The story features a main character who gets reincarnated as a slime and uses his unique powers to carve out a nation for himself and the monsters under his protection.
As a story set in a fantasy world,That Time I Got Reincarnated As a Slimenaturally features magic, with many different types and categorizations depending on the person casting the spell or the source of power behind it. Here are some of the best spells used in the series.
Updated July 24, 2025, by Danny Guan:The third season of That Time I Got Reincarnated As a Slime debuted during the Spring 2024 season, giving fans a deeper look into the lore and world of the series' universe. More characters and more conflicts are unveiled with each new episode, and a slew of new abilities and spells are also introduced in the process. With that in mind, here are some more spells from That Time I Got Reincarnated As A Slime, ranked by their power.
11Holy Ark
An Unparalleled Sealing Spell
While many powerful spells in theSlimeuniverse are powerful attack spells, there are also plenty of powerful utility spells at play as well. One such spell is Holy Ark, an incredibly powerful sealing spell belonging to the holy magic classification. Holy Ark is first shown having already been used to seal away Chronoa by Luminous, who keeps her locked away in secret.
Holy Ark creates a magical coffin that seals the target inside and isolates their soul from the world. This special aspect allows for two versions of the same person to exist at the same point in time. The coffin itself is filled with so much holy power that even Luminous, a True Demon Lord, is burned when she touches the coffin.
10Black Lightning
An Explosive Burst Of Energy
Black Lightning is a powerful Dragon Magic spell descended from Veldora’s Dark Lightning that can summon a bolt of lightning down on a target. Unless the target is able to resist it, they can be vaporized instantly.
Though it was originally part of Veldora’s Storm Magic spells, Black Lightning became an innate skill used by Tempest Star Wolves, who use their horns as a conduit for the spell’s power. Rimuru learned this skill when he used Mimicry to turn into a Tempest Star Wolf himself.Ranga would also learn the spellwhen he eventually evolved into a Tempest Star Wolf.
9Nuclear Cannon
A Blazing Heat Ray
Nuclear Magic is one of the most powerful types of Elemental Magic, requiring the use of Abyss Cores in order to successfully cast. Human casters often need to cast nuclear spells in a group, with the exception being powerful characters like Razen.
Nuclear Cannon is the basic Nuclear Magic spell, which demonstrates just how powerful Nuclear Magic can be. A powerful ray of heat that can destroy a physical body in one blast, Nuclear Cannon is one of the most powerful single-target spells in theSlimeworld.
8Daemon Summoning
Calling Dark Spirits From Another Plane
Summoning magic is an incredibly costly type of spell, one that costs a large amount of magicules to even cast. Furthermore, when it comes to summoning daemons, the daemons often require some amount of sacrifice, making this quite an expensive spell indeed. Still, the effects can be quite potent, as it allows the summoning of powerful daemons that are bound to the caster.
Rimuru casts Daemon Summoning in the midst of his conflict against the Kingdom of Falmuth. Of the three daemons summoned,the most prominent is Diablo, who becomes one of Rimuru’s most stalwart allies.
7Inferno Flame
A Fatal Baptism By Fire
Inferno Flame is the ultimate Flame Spirit Magic spell, which summons a torrent of flames that are even hotter than those created by Nuclear Cannon. Its usage of spiritrons allows the spell to pierce through any defense.
Though this spell is incredibly powerful, it requires the user to be in accord with the fire spirits. While this can be difficult for some, it is easy for someone like Shizu, who is possessed by Ifrit, a Greater Elemental of Flame.
6Nuclear Flame
A Landscape-Flattening Nuclear Explosion
Another powerful Nuclear Magic spell, Nuclear Flame was used by Lacuain his fight against Rimuru. The spell generates a powerful thermonuclear explosion, unleashing the force of Nuclear Magic in an expanded area rather than concentrating on a single target.
Though it had the power to destroy an entire area in a flash, Rimuru defeated the spell easily with his Beelzebub. Despite that, the spell was sure to have flattened the entire landscape had Rimuru not stepped in.
5Marionette Heart
Clayman’s Manipulative Magic Shackle
Marionette Heart is a Mental Magic spell that swaps out the heart of the target with a magical device, making them subservient and obedient to their master. The magical device can convey sound back to the caster, and the caster can turn the target into a Majin by sending magicules to the device.
This spell isone of the signature spells of Demon Lord Clayman, who used it to control his subordinates as if they were puppets. He kept the details of his spell a secret so that others would not be able to find a way around it.
4Nihilistic Banish
The Power Of Nothingness
Nihilistic magic is a special subset of dark magic that focuses on utilizing the power of the void and minus energy. Nihilistic magic is an incredibly advanced style of magic, and very few in the slime world can use it effectively.
Nihilistic Banish is an incredibly powerful nihilistic magic spell that functions similarly to Disintegration, though it uses the power of the void as its source of power. Though it is incredibly powerful, its use of minus energy means it can be countered rather easily by plus energy.
3Disintegration
Eradication By The Light Of God
Disintegration is the most powerful offensive Holy Magic spell. Anything in the spell’s range begins to experience spiritron decay and is destroyed instantly. The only flaw of the spell is its rather limited area of effect, making it less effective against large monsters.
There are stronger versions of Disintegration that increase its effectiveness, including Trinity Disintegration, which stacks Disintegration three times on top of each other. Hinata Sakaguchi has even been shown to imbue her sword with Disintegration, drastically bolstering her offensive power.
2Drago Nova
The Power Of Limitless Potential
Drago Nova is a True Dragon Magic spell utilizing the power of the Star King Dragon. It is used by Demon Lord Milim Nava, and it is essentially her most powerful spell.
Drago Novais a unique spell created by Milim Nava, and as a result, its particular attributes are not exactly known. It is, however, incredibly powerful and capable of leveling the landscape in a single moment. Milim can also cast a weaker version of the spell called Drago Buster that acts on similar principles. Though its power is lower, it is still an incredibly powerful spell capable of destroying monsters like Charybdis.
