Hakuzōsu. Just, Hakuzōsu. If you have ever wondered "what's the best way to annoy the hell out of anyone you're fighting in Pv P?", then Hakuzōsu is your guy. His kit revolves entirely around reducing all of your attacks to dealing miserable levels ofScratch Damage while his team laughs at your struggle. His Sheltering Shadow reduces all incoming damage by anywhere between 35 and 50%, direct or indirect, while his Awakening gives him a new passive, which lets him protect the ally with the lowest HP remaining and take all of the ATK inflicted to them. And if you're thinking his kit seems to have been designed with a specific intention in mind, you'd be right. Hakuzōsu was made specifically as a counter to Onikiri, where his absurd levels of Damage Reduction either negates or reduces the chances of an AoE proc happening, while eating the brunt of it like tofu if it does occur. As it turns out, this also makes him the most broken shikigami in the current meta, since he also makes everyone else deal pathetically-weak damage while his team sits behind an obscenely-strong protection. And if that's not enough, his passive gives him up to 60 extra SPD at the beginning of each match, basically laughing in the face of Rocket-Tag Gameplay since he will almost always move first, and the way his kit is usually built, he's also far too resistant to disable with CC. As such, players with Hakuzōsu are all but guaranteed to win in Pv P, even if they don't have the damage output to show for it, since with sufficient turtling, the other players will just Rage Quit after several turns of tickling him and his team.
Speaking of horrific SSR power creep, Onikiri seems to have been a result of the developers looking at Tamamo and saying "Yeah, we can do better than that". Simply put, his passive effect is just flat-out unfair. While he simply does absolutely horrendous amounts of damage with just his basic attack, his passive takes this to new heights with free strikes that deal terrifying Splash Damage that bypasses most manners of shielding, or Shōzu's Life-link. When built right and allowed to attack, his first move is a practically-guaranteed win, especially when equipped with Scarlet soul (counter attack on damage), so you'd better be damn sure your shikigami could off him in one move, or it's game over. Disabling him with controlling effects is the only remotely-viable way of shutting him down, which is harder than it sounds since his Evolution bonus is an increase to Effect RES, on top of the defensive buffs granted by his team. As a result, he really should be at the top of this list, as shortly after his release he became effectively the only DPS shikigami anyone bothers using at high levels (some players even use multiple copies, on the basis that if one OP shiki is good, 2 OP shikis is better). It got so bad that (rather than nerfing him, oddly) the developers had to release Hakuzōsunote A defensive shiki optimised to negate single-target damage, which prevents Onikiri's follow-up strikes as a hard counter to him. And even then, he's still a very dangerous foe if you come unprepared.
Less frequently used in PvP than most, but Shoyō is pretty damn terrifying. What makes him powerful is his "curse", which collects damage dealt to the victim and activates upon his second turn after casting, dealing a share of the memorized damage to the opponent. You're under his curse and the strong attacker on the opposing side failed to kill you, only leaving you within an inch of your life? Don't get too excited, because You Are Already Dead; come Shoyō's turn and you'll be finished off anyway. That is still not the full extent of this skill's power; it bypasses Shōzu's Synchronization, meaning that the collected damage will not be split among the team and will be fully dealt to the victim. The worst part? It cannot be removed via status-effect-removal skills and it bypasses status effect immunity. Not even enemies like Orochi (no, not the humanoid SSR) or Octopus are safenote As a result, his most common use is to deal with powerful world bosses. To top it off, both his special skills, one of which casts the curse when sufficiently upgraded, only cost 2 mana points each. He is especially powerful when fighting any Demon King style battles where you'd want to score as much damage as possible.
After a skill rework, Chin became one of the most OP shikis in the entire game, enough that she absolutely dominates any boss challenge. Chin on her own isn't that big of a deal- when she attacks a target, she gives it 2 stacks of her poison which do HP% damage on the target's turn. However, when her passive reaches the maximum level, any attempt to apply poison stacks to a target that already has the maximum of 5 instead does a massive burst of damage equal to 30% of the target's maximum HP (capped at 280% of Chin's ATK). Now, consider that poison stacks from multiple copies of Chin all count as the same effect and you're beginning to see where this is going. Equip your 2-3 copies of Chin with the Scarlet soul (counterattack on receiving damage, including transferred damage, itself universally considered completely broken), throw in the aforementioned Shouzu to ensure that any hit on any of your shikis will trigger a counterattack from your Chins, and watch enemies just get torn to shreds. While somewhat limited in PvP, when fighting targets with massive amounts of HP like area bosses the Chin-stacking strategy is often literally the only one worth using, as any glance at the damage leaderboards will universally show.
Shiranui is so broken it's not even funny. Shiranui allows all of her teammates who launched a normal attack a 50% chance of doing it again (raised to 100% when fully upgraded) and adds Life Drain to that second attack, which may not sound all that impressive, but when her team has those that deal obscene amounts of damage in one tap, it gets really serious. Doubly so if the damage type is indirect, scales damage to your own shikigami's HP, triggers everytime anyone on their side moves, and hits everyone on your team at once, such as that of Bake-kujira, and lord help you if she herds around more than one of that shikigami. Shiranui herself hits like a truck, possibly twice every turn, and has a passive that seems to have been deliberately cooked up to prevent the previous Game Breaker extraordinaire, Onikiri, from taking her out quickly, in that it gives her a guaranteed Heroic Second Wind that nobody can bypass. This way, she's guaranteed to survive your initial assault regardless of how much damage you deal to her, and unleash a barrage of hits on your team that hurts a lot, especially if she's the last one standing. Really, fighting Shiranui is extremely unpleasant if you lack her hard counters, of which she has virtually none. The most practical way to fight her is to hunker down with Damage Reduction skills, which usually requires yet another Game Breaker, Hakuzōsu, and keep smashing her silly until she finally bites it.
Kuro Doji and Demoniac Shuten Doji are devastating together. Kuro Doji gains free AOE attacks when he loses HP. When his skill is active, Demoniac Shuten Doji damages his teammates on their every turn and boosts their attacks proportionally to HP lost. Thus the more turns Kuro Doji gets, the more health he loses and the stronger he becomes. And while this team-up isn't very useful for prolonged fights, such as encounter bosses (since it's fairly easy for Kuro to get killed), it reigns supreme in any multistage battles, be it Secret Zones, Area Bosses, Netherworld Gate, or even Ultimate Orochi.