Isekai anime have more freedom than non-isekai anime. By taking the main characters out of the real world and placing them in a fantasy world, the best isekai anime can operate by their own rules. This means that the main characters can live in a world with magic, giving them abilities that their previous world never had. Characters like Tanya van Degurechaff from The Saga of Tanya the Evil were normal people in their previous lives. However, in their new lives, they are powerful characters capable of causing havoc.
The main characters in Isekai stories are often given a special power when they enter a new world, making their battles more interesting. Regardless of what abilities are shown, a good isekai battle can rival the best battles in anime. They can also set the tone for the show they're on, letting people know how intense things can get.
10 Carrion vs. Milim – That Time I Was Reincarnated as a Slime
Two Demon Lords Fight Each Other
That Time I Got Reincarnated as a Slime has one of the deepest and richest worlds in isekai anime. The world that Rimuru Tempest finds himself in is complex, to say the least. In Rimuru's world, there is a hierarchy of power headed by the Demon Lords. Two of the most powerful beings in the world, Milim Nava the Destroyer and Carrion the Beastmaster, fought a battle that shook that power structure to its very foundation.
Milim Nava is the strongest woman in That Time I Got Reincarnated as a Slime and possibly the strongest character. As the daughter of Veldanava, the creator of the world, she has access to True Dragon Magic that Carrion could only dream of. While Carrion transformed into his glorious Royal Beast Form, he was no match for the Dragonoid Milim. She used her Drago Nova on Carrion, and while barely hitting him, destroyed most of his country and a giant mountain in the process.
9 Tanya vs. Anson – The Story of Tanya the Devil
Magic Gunfire Never Looked This Cool
Saga of Tanya the Evil has one of the cutest and most dangerous isekai protagonists imaginable. Tanya van Degurechaff is a 12-year-old military leader, an expert on the battlefield, and a cold-blooded killer. Her battle with Anson and his army in the desert skies was Tanya's pinnacle performance. Tanya dashes away from her allies and into her enemies. She fires bullets in all directions, hitting enemies with blue and purple beams. Anson has a special shotgun that blasts Tanya and her allies out of the sky.
Tanya recovers and charges at her opponent with a knife in hand. She is able to stab Anson before realizing that Being X is possessing him. Being X latches onto Tanya before self-destructing. Unfortunately for Being X, Tanya's friends arrive in time to save her, helping her distance herself from Anson before shooting him in the body.
8 Rimuru vs. Falmuth Kingdom – That Time I Was Reincarnated as a Slime
The most one-sided battle Slime has ever fought
Rimuru Tempest has never really been one to enjoy fighting. He will fight to protect his friends, but that's about it. When Shion was found dead, all doubts were dispelled. Rimuru finds the invading Falmuth warriors and unleashes one of the most one-sided spells in the anime. Rimuru flies into the air above the soldiers and unleashes Megiddo. The spell works by creating tiny water droplets in the air, which then reflect light beams. Those beams are then focused into lasers and fired through the heads of Rimuru's enemies.
This attack is extremely effective because the attack itself does not use magic, natural energy, or anything other than sunlight to kill the opponent. Megiddo wiped Falmuth off the map before they could engage in battle. Rimuru then used the souls of the people he had just killed to transform into a Demon Lord, gaining more power to terrify his enemies.
7 Dead End vs. Dragon God Orsted – Mushoku Tensei: Jobless Reincarnation
Rudeus never stood a chance against Orsted.
Mushoku Tensei: Jobless Reincarnation is a popular anime with top-notch graphics and animation, a rich world, and a great cast of characters. It's not a show known for its fighting scenes, which makes Rudeus, Eris, and Rujierd's fight against Orsted that much more awesome. As Dead End makes their way home, they run into the Dragon God himself. Rujierd and Eris are completely terrified of Orsted because of his innate abilities, but Rudeus isn't. Because he is not as fearless as his companions, Ørsted knows that he knows Hitogami, the Human God and Ørsted's enemy.
Orsted charges at the trio and attacks Rujierd first. Rujierd has been unstoppable up until this point in the series, but Orsted makes him look like an amateur. After tossing Supierd aside like he was nothing, Orsted kills Rudeus and tells him to let the Man God know he's coming.
6 Shadow vs. Aurora – Greatness in the Dark
Shadow Finally Enjoys a Fight
Shadow is definitely the strongest in The Eminence in Shadow. He is so powerful that he is almost always bored and is happy to fight anyone who can challenge him. He couldn't be happier when Aurora, the Witch of Calamity, is summoned to be his rival in Sanctuary. She is the main antagonist of the new world he was brought into by the isekai and one of the few people who can keep up with Shadow.
Their fight was beautiful. They moved back and forth like ballerinas, every participant smiling broadly. When it came time to end the fight, Shadow commented that he was happy to face Aurora but disappointed that he couldn't fight her at full power. He charged through her Blood Magic before defeating her with a single slash of his sword. The two ended the fight with smiles.
5 Lloyd vs Guisarme – I was reincarnated as the 7th Prince so I could slowly perfect my magical abilities
Lloyd had to use all his strength.
I Was Reincarnated as the 7th Prince has great action scenes with complex yet easy to understand magic. Lloyd loves learning new magic and is constantly looking for someone strong enough to try it out on. While most of the characters in the series aren’t even strong enough to make Lloyd sweat, the demon lord Guisarme is strong enough. He takes over Jade’s body to use Jade’s incredible teleportation technique and effectively fights Lloyd. While Guisarme certainly puts up a good fight, Lloyd’s passion for magic is too much for him.
Lloyd learned to dodge Guisarme's deadly Shadow Wolf ability as soon as he saw it. It was ironic that Lloyd got bored after fighting Guisarme for a few minutes because the fight was nothing special. Lloyd ends the battle by using Guisarme's strongest ability, the Deathly Dark Orb, with ease.
4 Garfiel vs. Elsa – Re:Zero – Starting Life in Another World
Garfiel's joining the Subaru team has paid off handsomely.
Re:Zero – Starting Life in Another World is another isekai anime that isn’t known for its battles. However, when there are battles, the stakes are high, the action is very explicit, and there’s a good chance that someone is going to die. Elsa is one of the scariest characters in all of Re:Zero. She’s at least a psychopath who enjoys hurting people. She was actually the first person to kill Subaru in season one and hasn’t stopped her killing spree since.
She returns to kill the main cast, but this time, Garfiel is there to protect them. He does a great job of this, fighting the assassin in a fierce battle before finally killing her for good. His fighting is brutal, bloody, and has all the hallmarks of a twisted series like Re:Zero.
3 Shadow vs Beatrix and Iris – Greatness in Shadow
Even when it was two against one, Shadow didn't break a sweat.
Shadow's fight with Beatrix and Iris wasn't a real fight. Instead, Shadow entertained the two girls until he got bored, but it was entertaining for a while. The trio danced around the city while Beatrix and Iris used everything they had against Shadow. Their sword skills weren't bad, but they were nothing to worry about for the leader of Shadow Garden. After fighting the pair for a while, Shadow was ready to end it. He sat down with the girls, pointed his sword in the air, and covered the entire city in a purple-black light.
The girls were terrified. They thought Shadow was going to wipe out their city. Instead, Shadow said he would become Atomic and simply disappear. It's a hilarious ending to one of the best fights in the series and makes Beatrix and Iris feel silly for thinking they even had a chance.
2 Ainz vs Shalltear – Overlord
Perfect replica of an MMO war
Overlord did a great job of showing what an MMO battle would be like in anime format. Ainz Ooal Gown is the leader of the Great Tomb of Nazarick, the most powerful organization in the world. One of his strongest warriors, Shalltear Bloodfallen, has been taken over by outside forces and is looking for a way to fight. Ainz finds her on the battlefield, fully armored and ready to fight. However, before fighting her, he cast dozens of buffs on himself like a real MMO gamer would do.
While Ainz is one of the most powerful beings in isekai history, he does not want to kill Shalltear. He knows how valuable she is and realizes that she is probably under some kind of mind control at this point. After preparing all his buffs, Ainz uses his Super Tier spell, Fallen Dawn, to level the battlefield and set the tone immediately.
1 Makoto vs. Sofia and Lancer – Tsukimichi: Moonlit Fantasy
Makoto first launched and the world felt it
Makoto Misumi suffered when he was transported to his new world by isekai. The Goddess disliked him because she thought he was ugly and banished him to the wastelands of the continent. Luckily for Makoto, he found some great friends to support him when the Goddess didn't. Unfortunately, this wasn't the only time Makoto suffered because of the Goddess. Later in the series, Lancer and Sofia ambushed Makoto after he was transported by the Goddess against his will. Not only did the Goddess get him into trouble, but Lancer and Sofia fought him because they thought he was fighting on her behalf.
They were able to cut off two of Makoto's fingers, which angered the World Traveler. He decided to let loose and broke off some of his Draupnir rings, charging himself up with power. Makoto then flew into the air, launching a powerful arrow at his enemy. The arrow hit its mark, cutting off one of Lancer's legs and destroying Sofia's armor. This is one of the most refreshing moments of revenge that Tsukimichi, or any isekai, can deliver.
