Unmarked spoilers are ahead, per Spoilers Off rule.
The 2021 anime's second episode shows just how much more creepy Ren's Slasher Smiles and maniacal laughter look compared to the early manga and the 2001 anime thanks to the new art style, but what really takes the cake is the blood you see on his face when he gloats about how he's finally going to take Amidamaru for himself after having just knocked Yoh out with an attack used through 100% possession.
Faust torturing Manta in front of Yoh. Made all the worse in the manga and the 2021 anime because Faust eviscerates Manta and leaves him pinned to the ground with his organs sticking out while he fights Yoh. At least the part with the organs sticking out is censored in the 2021 anime.
Due to what he did to Manta, Yoh is unusually angry throughout their whole fight, as in, at white pupils levels of angry. Not many things manage to piss him off that way.
Faust VIII's skeletons in general. The gigantic one he manifests when Yoh pisses him off takes the cake, though.
Faust's final Over Soul, 'Mephisto E' "the E is for Eliza". Is a giant, demonic nurse, whose hands are all Edward Scissorhands but with scalpels, syringes and other medical equipment. A perfect nightmare for anyone Afraid of Needles, especially, as Faust puts it, "my dear wife has always been quite clumsy..."
And what happened to Faust when Yoh accidentally pressed his Berserk Button: insulting Eliza. From a cold, cruel, snarky sadist always in control to an Ax-CrazyScreaming Warrior in one, two, three... Faust beats Yoh outright, and nearly kills him.
When the Spirit of Fire opens its mouth to a wide toothy maw especially since it's normally The Blank with two eyes and markings. Its normal appearance isn't much better, as it is a giant, antlered, vaguely humanoid red giant.
Special mentions goes to the imagery of the Spirit of Fire devouring Shamash (Jeanne's god-level guardian spirit) who has the appearance of a disturbing blank-eyed, tailed, giant BABY. The wriggling motions of its body as it's being eaten make it worse. It's been YEARS and I can't get the image out of my head...
The abilities they display in the final fight against Shaman King Hao]] are impressive but also goddamn scary. The Spirit of Fire casually throws around magma exceeding 1200°C, the Spirit of Thunder can generate massive storm clouds, lighting of 1,500,000,000 KW and a voltage of 100,000,000 V, as well as magnetic field strong enough to stop solar attack that could destroy entire earth, the Spirit of Earth can control gravity, manipulating meteor rain without problem (and according to Pascal Avaf, is responsible for creation of metal and gives life to plants), the Spirit of Wind has incredible speed and attacks with sharp winds and debris, with gust of 120m/s, and a pressure of 900hPa, and the Spirit of Rain can create unlimited amounts of holy water, massive icicles and blizzards (in combination with Spirit of Wind). There is a good reason why Elemental Warriors have to go through literal Training from Hell to control them, and why Patch entrusted remaining Spirits to four Kings of Hell (Mephistopheles, Anubis, Izanami and King Enma) after Hao stole Spirit of Fire. Though in the manga, Hao demonstrates multiple times what happens when this power falls into the wrong hands.
Hao, as far as we know, isn't an Elemental Warrior. Meaning that either Hao is strong enough to control Elemental Spirits by his raw power alone... or that the Spirit of Fire joined him willingly.
As scary as the powers of Elemental Spirits are, they pale in comparison of the power of The Great Spirit once Oversouled by Hao, in the manga and 2021 anime at least. To witness: it can create an artificial star that can produce solar flare and solar prominence as an attack, and it can collapse that star into supernova, with residual taking form of a black hole, with all what that implies. It can also summon meteors and comets. Keep in mind that its powers are basically limitless.
Tokagero in his first appearance in Volume 3, both in his normal and a deranged skeletal version prior to him possessing Yoh, leading to his Heel–Face Turn.
Tokagero's backstory is both this and a Tear Jerker. When he was young, he and his mother were very poor and risking starvation, so she sacrificed herself to feed her son with her flesh. After that, Tokagero became a bandit and formed a gang that robbed everything they could lay their hands on, until Amidamaru ended their pillaging by slaughtering them to the last. Due to the way he died, Tokagero was unable to move on, and became so resentful towards Amidamaru that he sought revenge, long after their deaths. In his obsession, he possesses Ryu against his will, steals Harusame from its museum and tries to kill Yoh with it.
Tokagero makes one hell of a Nightmare Face when he possesses Yoh. Although Yoh often grins, it's not normal to see him do so with his eyes wide open, and with white pupils, and holding a knife near his throat. Fortunately, Tokagero couldn't bring himself to kill him and had a breakdown.
The Tao family in general, given their work with jiangshi. They like employing nightmarish undead in squads and armies, and when they kill even more people, the new dead are easily integrated into the ever-growing Tao army. And that's not even getting into how the Tao family modify zombies, by mixing and matching the corpses from even different species to create powerful zombie soldiers.
Tao Yuan/En, before being revealed as a normal guy had demonic fangs in one scene. His mistreatment of Ren and Jun also counts. No normal father would chain their children in a dungeon.
Ren's first fight with Yoh immediately shows how much of a No-Nonsense Nemesis he is, when he nearly guts him like a fish at the end. In the 2001 anime He outright sends Yoh to the hospital with the sheer wound he dealt to him. Yoh does get his payback the next day, but it still takes him a while to fully recover from that blow.
Chimimoryo, tiny animal spirits with deranged eyes that the BoZ Brothers attack Yoh and his friends with and, during their first encounter with him, try to defeat him and steal Amidamaru from him with. According to Tamao, they're spirits that have forgotten what they used to look like.
The power of Reishi (Reading the Heart). It's an ultimate Blessed with Suck power, a case of A Mind Is a Terrible Thing to Read turned up to eleven. Uncontrollable mix of telepathy and empathy that is working 24/7 and forces shaman to hear and experience thoughts, emotions and desires of pretty much everybody around them to extent that it borders on mind rape. When enough of negative thoughts gather, they create Oni (see above). As a shaman's power grows, so does reishi. Aside from obvious mental and emotional trauma it causes, reishi also causes trust issues that border on paranoia. While this sounds more like tear jerker, it becomes nightmare fuel once we learn that only way to get rid of it is by trusting somebody. In a sense, the ability ensures that it won't be (easily) rid off.
According to Hao who has had this power since his early childhood, so some 1000+ years, reishi is also generated by intense feelings of loneliness. While it is scary and tragic enough, according to him, every shaman has the potential to develop it. All that is needed is lack of proper emotional support and you get stuck with it. And as the manga showed us, many shamans experienced bullying and alienation by humans on basis of their powers. This also implies that people who need help most (like, say, neglected children) are in biggest danger. Oh, dear Great Spirits...
Anna had this power as child. She developed it because her parents were scared of her strong powers and neglected her because of them, so she needed to find way to interpret their feelings about her besides interpreting their faces- implying it was case of Be Careful What You Wish For. Then she got reishi, her spiritual powers grew, she started manifesting demons, and her parents abandoned her. And this all happened before she was ten! Due to this, she became reclusive - as just going out in public was enough to cause her to start summoning demons who hated everybody. Then she created the Oh-Oni, who called her mother. Creepy enough, except that in order for it to grow stronger, it had to eat other demons she summoned. If it weren't for Yoh and Matamune, Anna may have either died, or spent the rest of life captive of a murderous, violent demon. Best case scenario, she would have remained a bitter, hateful recluse tormented by her powers for the rest of her life. In the worst case, she may have turned out like Hao...
Hao got reishi when he was child, still going by name Asaha/Mappa Douji. He got it by over-using his first Oversoul and accidentally absorbing his first friend Ohachiyo, small demon who took care of him after his mother's death. Hao at first loved power, which he got with Oversoul, as it allowed him to predict attacks of people sent to kill him because they thought he was demon ( which in itself is worthy of nightmare fuel). However, then it turned out that monk sent to kill him, Densen Hoshi, was same man who murdered his mother and burned down Hao's home. Not only that, but man didn't even believe that demons existed- he was perfectly aware that both Asanoha and Hao were humans, and yet Would Hurt a Child and burn innocent woman for sake of money. Hao didn't take well to this and murdered the man, by smashing his skull. Ohachiyo was then absorbed and his last words to Hao were that they couldn't be friends after all and that he (Hao) is same as humans who hurt him so much. He was around five at that age. It's hard to decide which is scarier and sadder getting power due to wanting to understand why you are neglected by your own parents or due to absorbing your best friend...
Unlike Anna, he could somewhat control demons he created, by keeping them sealed within his own body, though when they got out, they could overrun whole capitol and required main onmyoji and his apprentice to get rid of them which eventually, as shown in Shaman King Zero, led to it's own set of problems and another traumatic experience for then preteen Hao, or even weaponize them by willingly fatally wounding himself and allowing oni to enter target, eating their soul from inside out. However, his reishi never could be controlled, and being constantly exposed to negative thoughts and emotions, along with discrimination he received as shaman, being feared and mistrusted for his powers, always lonely and seeing destruction of nature led him to being drivenmad and bitter, convinced that humans are utterly sinful creatures that will destroy the world unless exterminated. And rest is history... In a way, reishi could be said to be responsible for the entire plot of the show.
Hell, just how completely and utterly ruthless both Hao and his followers and the X-Laws are. They will both mercilessly kill anyone who dares defy both their leaders, and have both ended and ruined multiple lives, the X-Laws just to destroy Hao, and Hao and his followers just to exterminate humanity. No wonder Yoh said that they both were not so different.
for example, The Family-Unfriendly Death that Hao inflicts on his opponents, burning them to bones then ashes. Also the torture themed version that Jeanne inflicts on Team Niles. The 2021 anime shows them fully animated, and it still manages to be messy as hell despite Gory Discretion Shot being somewhat in effect.
Volume 24 gives us zombie soldiers, though they're curb-stomped by Team Gandhara very quickly.
Volume 26 gives us a Sphinx with very large eyes.
The Ogre Slayer Over Soul can reduce anything to bone.
Volume 28 gives us Mastema, a frightening demon of hatred.
Bron is a very disturbing Patch. His appearance is gross, his face looks deranged, has a psychotic look (even more after Lyserg burns him) and he can also morph into a huge spider while keeping his head.
When Anna slaps Hao, he doesn't cow to her. He doesn't do anything you would expect. Instead, he catches her hand and tells her that she's worthy to be his wife. He doesn't kill her, but he makes it abundantly clear that despite her ability to bring all others to heel through force of will, the only power she has at the moment is the power he lets her have, and if he so chose he could kill all of them there and then.
Late in the first anime, the attack Luchist and Lucifer unleash on Ren is too fast for him to react, severely injuring him and leaving him unconscious in a pool of his own blood, while Horohoro can only scream his name in horror. Fortunately Faust and Eliza save him.
The sixty-first episode of the 2001 anime has Hao grabbing into Yoh's abdomen and pulling out his soul, and then proceeding to actually inhale said soul into his mouth. He calls this technique "spirit digestion" in the episode after that. You could even see the huge shock Yoh's friends had on their faces from what they just saw happen. The fact that Anna had just as shocked a look on her face from what she saw as well and screamed Yoh's name in disbelief didn't help lessen the terror, either. Luckily for them, Yoh gets better in episode 63.
In the manga and 2021 anime, how second round of the Shaman Fight begins is this, especially if you're acrophobic. To elaborate, everyone is boarded to plane heading to America. Mid-flight, Goldva reveals that it's in fact a giant Oversoul and dissolves it in air. Now imagine you're in a plane thousands of miles above the ground and it just blinks out of existence. 2021 anime is even worse as it shows it all animated, sudden disappearance of the plane and people's reaction to it. At least it didn't happen above the ocean.
Lilirara's attempt to stop Team Yoh from participating in the second round of the Shaman Fight has her summoning the four Seminoa Warriors, which proceed to cut Ren's leg off, following it up with piercing Yoh's heart, slicing Ryu in half, and tearing off Horohoro's arm. Thankfully, it's only an illusion conjured by her. But then, she shows them what happened 500 years ago when the warriors challenged Patch Hao, and as he tears them apart one by one, the same illusion that made us think what happened to them was real happens again before they get sent back to reality. And thank goodness reality once again shows they're still okay and in one piece, but still, the thought of an illusion making you think you've lost a body part, been sliced in half, or stabbed through the heart is frightening.
And there's her demise in the hands of Hao, especially in 2021 anime where it's shown in fully animated glory. First she's impaled by Spirit of Fire's claws, then she's burned to the ash that you can see scatter in the air. Sleep well.
Goldva losing her sanity and Laughing Mad while raving about how Hao is now the new Shaman King before she attempts to kill everybody. If you look closely during her rants, you'll notice that Lip and Lap are both sporting Dull Eyes of Unhappiness during the whole while - and that's because they both had their souls absorbed by Hao. And speaking of him, that's just the start of the fun: just seconds later, she's immediately killed by Hao's now zombie-like body, who proceeds to absorb the souls of everybody in the tenth plant except for Opacho and Rutherfor. Even having his head cut off by Yoh doesn't stop him from absorbing his soul afterwards. That doesn't even stop there; during Hao's awakening as Shaman King, you can see bright glows of red and white enveloping everybody beyond the tenth plant, which even extend beyond Mu to everybody inside Anahol's Sphinx, of all things! All this especially takes the cake in its fully-animated glory in the 2021 anime. Hope you have a good night's sleep!
