That One Boss / Yu-Gi-Oh!

Unless you've got the Heart of the Cards on your side, these bosses will waste no time in stacking the deck against you.

  • Yu-Gi-Oh! Dark Duel Stories:
    • Simon Muran/Paradox. His deck is full of magic cards that can reverse the flow of the duel, and he gets them with shocking frequency. Brain Control to take your strongest monster for an attack or tribute, Crush Card Virus to wipe out your field of powerful monsters, Spellbinding Circle can weaken all your monsters to make defeating them easier, and Dian Keto the Cure Master to restore 5000 of his Life Points for more chances to beat you. Oh, and he has 3 copies of Brain Control, Crush Card Virus, and Spellbinding Circle to hit you with. All of this on top of a solid Light/Dream Deck that uses Bright Castle to increase the power of his monsters, and Simon more than earns his place here.
    • Ishizu Ishtar. She uses a female monster deck like Mai, but is significantly more powerful due to her potent magic cards and stronger monsters. She runs 3 copies of Dark Hole, and her A.I. is smart enough to play them before summoning a monster to attack you directly with. Next are her 3 copies of Megamorph and Spellbinding Circle, using the former to power up her monsters one at a time without a type restriction to hinder them like similar cards and the latter to weaken all your monsters at once. She even runs 3 copies of Swords of Revealing Light, giving her a potential 9 turns to stall and build up her forces while you sit there and pray for her current copy to end before she uses another.
    • Priest Seto is ridiculous, even compared to his fellow Ancient Egypt bosses. He uses almost the exact same monsters Seto Kaiba uses in Domino City, so get ready to eat Blue-Eyes if he lands it, and possess far more powerful magic cards as well. He stocks 3 copies of Dark Hole and Raigeki, giving him 6 total field nukes to play against you, and Raigeki leaves his field untouched. 3 Megamorhps to power any monsters of his he wants, meaning his beatsticks like Blue-Eyes White Dragon hit harder. Most dangerously, he possess 3 copies of Change of Heart, which is a Game Breaker in Dark Duel Stories because it's permanent unlike the real life card. He can either steal up to 3 of your strongest monsters from you to beat you with, or tribute them for one of his own monsters.
  • In 7 Trials To Glory, we have the imaginatively named R. Hunter, one of the game's Shadow duelists. The game's main gimmick is the Shadow World, which allows both players to use absurdly broken Shadow decks. R. Hunter uses a Shadow version of an Exodia deck, which allows him to summon Exodia within about 5 turns. And that's if you're lucky; if not, say hello to a 2-turn instant loss. It really says something when Marik, who has three copies of each of the Envoys in his Shadow deck (which were Game Breakers in the real life game even after being limited to one), is much, much easier to beat than R. Hunter.
  • The Four Clone fight in Stardust Accelerator is unanimously considered the most difficult fight in the game by a huge margin. As the name implies, it is a Boss Rush, so you cannot simply restructure your Deck to beat one or the others will crush you. The first one is hard but not ridiculous, the second is a pushover, but the third will absolutely wipe the floor with you unless they get ridiculously unlucky. And the fourth is even worse than the third, running a TeleDAD deck (which, for those not familiar with competitive play, was widely considered the most dangerous deck anyone could run at the time Stardust Accelerator was released). And to make matters worse, your Life Points carry over to your next opponent for no good reason. Did you just barely beat your third opponent with a few hundred Life Points left? Yeah...good luck. Oh, and if you're planning on boosting your life points to stock up for the last fights? So sorry. The game rounds down whatever life you had to 10000 for each fight, but never rounds up.
    • Though not nearly as bad as the Four Clones, there's also Lenny. You face him very early in the game, where it's unlikely you'll have any powerful monsters with over ~2400 ATK, or many monster removal cards. Lenny plays an incredibly nasty Insect deck filled with 2600-2800 ATK monsters that he can summon for virtually no cost, and loves to spam Dimensional Prison every time you try to attack him.
  • Yu-Gi-Oh! Forbidden Memories gives us Priest Seto, in your third encounter with him. Easily the most challenging opponent in the game, primarily for a single card: Blue-Eyes Ultimate Dragon. Which in this game is treated as Normal Monster. Monster removal cards are incredibly hard to come by in this game, but in this duel, they are an utter necessity, as there is no card in the game that can overpower Blue-Eyes Ultimate Dragon even with a Guardian Star boost. And just to add some far too much Fake Difficulty into the mix: you fight Seto at the end of a long Boss Rush campaign, which lacks any chance to save. Which means you WILL have to fight these guys over. And over. And over again. Oh, and by the way, Seto isn't the last battle in said Boss Rush. Who is? Why, the final boss, of course. Thankfully, even the final boss isn't as bad as Seto, but if you get bad draws... well, let's just say tears will be shed.
  • Marik Ishtar, in almost every game he appears in. He's a Bonus Boss in Dark Duel Stories, so he's meant to be one of hardest challenges in the game the player must seek out on his own, therefore not eligible for this trope. In Yu-Gi-Oh! The Sacred Cards he is spared from this only by virtue of being the final boss, as he is far and away the most difficult opponent in the game with multiple cards that reverse the entire flow of the game in a heartbeat. In 7 Trials to Glory... well, see the R. Hunter entry above, and note that he also has three copies each of Mirror Force and Torrential Tribute. He's at his worst, however, in Yu-Gi-Oh! Reshef of Destruction, where he will throw out monster-destruction cards like breadcrumbs, weaken your cards to near-nothing (when they're weaker than his for the most part already anyway), and constantly summon multiple monsters per turn when you're lucky if you can destroy one a turn. And apparently, he was just testing you. Yeah.
    • Marik's dragon, Odion, may be one of the hardest opponents in some games. Since his deck seemingly consists of 50%-70% trap cards, you'll be pretty much helpless unless you use Jinzo or some other card that makes traps useless. His appearance in The Sacred Cards is an exception; he has almost no trap cards worth noting in his deck in that game. No, he's That One Boss for a different reason. In a game where four-star monsters with ATK over 1500 are a very rare commodity barring insane Level Grinding, having an opponent spam monsters well above that including some that hit 1950 without tributes really freaking HURTS.
  • Yu-Gi-Oh! GX: Spirit Caller:
    • Hell Kaiser Ryo/Dark Zane. Matches with him go one of two ways, you steamrolling him, or him steamrolling you with his Chimeratech OTK deck. You can lose this battle easily if you get a bad hand. Worse, Hell Kaiser Ryo/Dark Zane is a shadow duel and he can't be registered, so you can stumble onto him while spirit hunting in the post game. Lose to him, and it's game over.
    • Titan. He uses a deck the boils down to Random Number God on steroids. All his monsters have effects that can negate your monster effects and destroy them, or destroy any monsters that attack his. While it's supposed to be a double edged sword kind of deck, Titan has an uncanny ability to get nearly all of his rolls in his favor, resulting in any of your attempts to gain an edge against him falling flat on your face. Really, no matter what deck you're playing, duels against him boil down to how generous the RNG feels like being, and more often than not, no matter how much you prepare for him, he will get his RNG based shenanigans going no matter what.
    • Kagemaru. You must duel him 3 times in a Sequential Boss battle, and he'll use a different Sacred Beast focused deck in each duel. All 3 of his decks are well built to summon each Sacred Beast it's themed around, and come with powerful support and destruction cards for tearing apart his opponents. Worse, you can only progress in the next stage of the boss fight by defeating him after he summons a Sacred Beast, so it's possible to lose while you're stalling for him to play one.
  • In Yu-Gi-Oh! 5D's World Championship 2011: Over the Nexus, you and Kalin will face Lawton in 2 on 1. But the thing is he starts with ten freakin' cards and he will burn your LP into a critical amount the first chance he gets. Unless you've got some card that block effect damage, be prepared to lose a lot of life points when it's his turn. Worst case scenario, 7600. In one turn. There's also a 50% chance that Lawton will go first, in which case your computer "partner" Kalin will move after that, likely running into some kind of damage-dealing trap. And then it's Lawton's turn once more before you finally get to play. If you haven't lost by then...
    • Before then, you'll have to face The Enforcers. Kalin is pretty easy, despite having some few powerful cards. Crow uses an average Blackwing deck, and despite having a solid synergy, his other cards lack the punch. Jack uses some powerful monsters, but you can manage with some destruction Spells and Traps... and then you duel Yusei. Yusei uses a Quickdraw Dandywarrior deck, known for being the top tier tournament deck at the time. While this is a fair one-on-one duel unlike the above, this is halfway through the game, and there's no way you're ready to facing that kind of deck yet (Keep in mind that losing against any of those people will not force you to retry again, unlike the above).
  • In World Championship 2004, every single one of the higher level duelists have no strategy other than "Use Black Hole/Raigeki to wipe out all your monsters." They almost always have multiple Mirror Forces, Magic Cylinders, Negate Attacks etc. put down. You'll use up half your hand getting rid of their traps and stopping their monsters, finally take something out of their life points... then they play Black Hole and you have to find an entirely new way to get past their defenses. Even worse, they have more than three copies of some cards which you're legally only allowed to have one copy of in your deck. What's more frustrating is that World Championship Tournament 2004 has a "luck" system where the AI will immediately draw these monster destruction cards if it starts losing, ensuring the player cannot keep a powerful monster on the field for long.
  • World Championship 2006 had some really tough Theme Duels, such as the Spell Counter (Use 15 spell counters & win), Dark Scorpion Gang (Use Dark Scorpion Combination and win) and Victory D. (Win with said card) duels.
    • A few of the Limited Duels were just plain messed up as well, such as No Setting Cards, No Attacks & the dreaded No Normal Summons, since the programming couldn't restrict the cpu opponent to do the same.
  • In World Championship 2008 we get Speed Guardigan Ferrario. The battle consists of three straight duels where he changes his deck every time and you do not get any recovery in between.
    • Later on, there's Sky Guardian Sefolile, which is the same thing, but FIVE duels in a row.
    • One of the hardest tag team duels in the game is Spirit Reaper and Marshmallon. Their strategy revolves around Final Countdown, which ends the duel in their favor if you can’t win in 20 turns, Nightmare’s Steelcage, which stops either side from attacking for 2 turns, Stumbling, which forces any monster summoned to be turned to defense mode, Spell Absorption and Solemn Wishes, which increase their LP by 500 points every time a spell is activated and they draw a card, respectively. They also run a ton of monsters that can’t be destroyed in battle or bounce your cards to your hand, like Marshmallon, Spirit Reaper, and Wall of Illusion, as well as Waboku, which negates any battle damage.
  • Jaden's storyline in Yu-Gi-Oh GX Tag Force 2 gives us a tag duel against Sarina and a mirror image of Sarina. Who are both running Exodia decks that abuse a loop of Card of Safe Return and Manticore of Darkness to run through their entire deck in one turn.
    • Pairing up with Viper in Tag Force 3 is a nightmare, because his A.I. is one of the dumbest in the game. If you only have one venom monster to defend you and the trap card "Offering to the Snake Deity" is set, he'll use it as soon as he can to blow up your only defenses and take out two of his. In short, he's not a big picture thinker, and he will frustrate you with his playstyle. Furthermore, the special duels (boss duels all players go through when selecting a partner from the "Partner 2" category) he goes against are all painfully terrifying. Crowler and Tyranno can overpower the venom monsters and blow up your Venom Swamps, Atticus and the Gravekeeper can swarm and disable graveyard access to Vennominon, and Amnael/Adrian are likely to remove your monsters from play, screwing up Vennominon from utilization.
    • Pairing up with Fontaine presents similar problems but on a different reason. Her deck isn't horrible, per say, but it has no sense of timing. She uses a Simochi deck which revolve around using bad reaction to simochi/nurse reficule the fallen one to deal the gains as damage. But as the AI doesn't use the cards in the correct order, she'll end up giving the enemy more lps than she would deduct. Not helping matters is that cards needed to support her are in a pack that's difficult to unlock in its own right.
  • In Yu-Gi-Oh! Nightmare Troubadour, there were several tough duelists, but the hardest fight has to be the boss rush of Big 5, Noah, and Gozaburo. Gozaburo uses an Exodia Necross deck with very little strategy and weak cards, so he's no threat at all, despite what the game says. No, the major problems are Big 5 and Noah. Big 5 uses a deck centered around Satellite Cannon, which is an annoying one-Tribute monster that cannot be destroyed in battle by any monster Level 7 or lower, and increases its attack by 1000 every turn, which then drops back to 0 once it attacks. Big 5 will keep Satellite Cannon in Defense position until it has several thousand attack, and then he will kill you with battle damage. If you somehow manage to defeat Big 5, you are faced with an even tougher opponent: Noah, with his fairies. Noah plays many powerful fairies and backs them up with The Sanctuary In The Sky, which eliminates all battle damage with battles attacking a Fairy-type monster. The major problem with Noah, though, is his ritual monster Shinato, King of a Higher Plane. This guy has a whopping 3300 ATK/3000 DEF. So you'll just Set monsters until you get something to kill him? When he destroys a Defense position monster, you take Effect damage equal to that monster's attack. Good luck killing this guy.
    • Gozaburo suffers from poor AI, but his duel is timed so you instantly lose in 20 turns, meaning you must defeat him in 10 turns or less. If he uses a Scapegoat card, you can lose anywhere from 1 to 4 turns.
    • The final possessed Joey fight is hard because you can't win or lose; you must force a draw using Ring of Destruction or Self-Destruct Button, both very situational cards.
    • Ryou Bakura is very tough early on, as he uses an Ectoplasmer/Call of the Mummy combo that lets him tribute monsters to damage you directly while keeping a fresh supply of monsters on his field to attack you directly. His second deck uses Vampire Lord and Patrician of Darkness, who can remove monsters from your deck and control which cards you attack.
    • Yami Bakura. In his first deck, he uses a Destiny Board combo, which results in an instant loss after five turns if you can't destroy it. His second deck uses Dark Necrofear, a very annoying monster who's summoned by tributing three Fiends in the Graveyard. Her effect is that, once destroyed, she controls the monster that destroyed her. And he has more than one.
    • Yami Marik is a difficult fight on his own but is made even more difficult with how you must win using your Egyptian God Card—who is vulnerable to traps like Mirror Force.
  • In Duel Transer, Odin's first encounter in story mode can become a major roadblock. Using a Water deck that excels at both beatdown and returning monsters to the hand. Chances are, by now, the player has built a deck that is reliant on Synchro Monsters, which are instead returned to the extra deck instead of the hand. And the numerous powerup effects of Spined Gillman and Umiiruka can make the deck incredibly challenging to face. If that isn't enough, Odin's extra deck includes Brionac and Trishula, who are staples of the limited/forbidden lists following the production of this game, but usually his non-synchro monsters will be powered up enough to force the player's synchro monsters into play, where the bounce effect can come into play. Thankfully, by the time the player has to face this boss again, who is now more powerful, the player will have access to more cards, which will make this less of a challenge.
    • Aside from Odin, plenty of opponents can become troublesome. If you're not prepared to remove Yusei's defensive Traps, he will have enough time to summon a strong monster and wipe the floor with yours. Crow can also be a problem when you don't have ways to prevent his swarming of the field. Also, among the 150+ Transcenders in this game, about ten of them are insanely difficult to beat, like the one using a combination of Final Countdown, cards that protect its Life Points and destroy your Spells and Traps easily, and the Fiber Jar. (Take note that the bonus building, Niflheimr, only has Transcenders... and most of them use multiple copies of limited/semi-limited cards. That Transcender? He has three copies of Fiber Jar. He just plays Final Countdown, resets the match with Fiber Jar, and before you know it, the 20 turns are over. Enjoy!
  • Yu-Gi-Oh! The Duelists Of The Roses has several tough bosses.
    • Tea is the first person dueled in the York Side of the game. Her Fairy deck is built around strengthening her monsters and weakening your own monsters with spells and traps, meaning if you don't get something strong and maintain it she'll chip away at your LP.
    • Mai has a mountain themed deck and terrain which strengthens her own monsters. If you picked the Zombie Deck to play with, Zombies lose strength on that field. Not to mention she has a card that disables defense mode and she enjoys getting out Harpie Ladies and Harpie's Pet Dragon, which gains strength for every Harpie on the field as well. Sure you can always bring out your Pumpkings if you got them...
    • Bonz has an insanely low Deck Cost, crippling your own Deck, while his Zombies gain power from the field. He also has Pumpking, which is a Game Breaker that increases the strength of his zombies by 100 points every turn, including itself. And if he has more than one Pumpking, those boosts stack. And Pumpking is very easy to fuse with low DC monsters, even when you don't have one to just play outright.
    • Yami Bakura runs the same sort of deck as Bonz, but with Plants, crippling your deck cost. What makes him hard besides that is the Crush terrain, which destroys any monster with over 1500 attack. To make matters worse, if you lose he accuses you of calling him a coward before boasting about how unstoppable he is.
    • On the Lancaster side, we have Pegasus, with his Millenium Eye, which lets him see your hand and every facedown you have. He doesn't even bother pretending he can't see your facedowns, which most of the others will do at least some of the time. Not only can he evaluate attacks correctly against your facedowns AFTER terrain effects, even when yours is boosted, he is smart enough to use Change of Heart and Brain Control to do direct attacks against your Deck Leader when they are possible (and ONLY those times). Even when a human wouldn't know that the one with the highest attack is by your Deck Leader facedown, he KNOWS, and WILL cast Brain Control, and WILL hit you for 3000+ points with your facedown. Pretty much your only chance is to use game breakers of your own back. Fortunately there are plenty of them to be found, some of which are available your first playthrough if you picked Lancaster first.
    • Weevil is no slouch either, and has one of the most broken cards in the game, Perfectly Ultimate Great Moth. As long as it's in defense position, it drains all your monsters 100 attack and defense each turn. Even the facedowns, revealing which are spell/trap and which are monsters. He doesn't always get it out, but if he does, you will have a lot of difficulty winning. Even if he doesn't get it out, he, like everyone else in the game, knows how to fuse well, and if you don't, he will stomp you.
    • Rex's dinosaur monsters are powered up by Wasteland terrain, making them incredibly strong without the need for fusions. If he gets lucky with fusions he can summon Bracchioraidus, crippling your chances at winning.
  • Joey Wheeler can be this in games where his deck is based around die rolls or coin flips. No matter how strong your monsters are, you have no defense against luck, and cards like Fairy Box, Needle Wall, Dangerous Machine-Type 6, Graceful Dice, and Skull Dice make for a very long, tedious fight. It doesn't help that Joey's stronger cards, like Panther Warrior and Gilford the Lightning, are also added to the mix.
  • Yu-Gi-Oh! Capsule Monster Coliseum has several tough opponents, particularly in the later stages of the game.
    • Seto Kaiba's first stage is very troublesome because it has many areas where you cannot move, but his monsters can get around it and attack you easily.
    • Marik's stage is a box of squares that power up certain attributes, forcing you to pick battles carefully. His strongest monster is Zoa, which has a huge amount of attack strength that's boosted even more if he lands on a dark space. If you don't take Zoa out immediately, it can defeat weaker monsters with one hit.
    • Yami Marik's second stage takes place on a volcano that erupts. Any monster standing in the lava gets a huge boost to attack, but takes damage if they're not Fire-type. Most of his monsters are Fire-type, and many have long attack ranges. If you're not careful, he can defeat your monsters with one blow each.

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