History YMMV / RabiRibi

** The red flowers commonly found in the Volcanic Caverns. Unlike their yellow and blue cousins, they use hitscan horizontal laser beams that deal abnormally high damage for a basic enemy, to the point where they can tear off about half your health bar on higher difficulties and outright one-tap you on lower ones. Fortunately, they die very quickly, but they also tend to be placed in locations where they have a line of fire with you and you don't have one with them, and said line of fire will usually aimed specifically to catch you off guard, like ''aimed right at a room's entrance.''

** [[spoiler:Miriam]] is the only boss that actively punishes you for completion (beyond the normal LevelScaling), as nearly every power-up you own adds to her list of very difficult moves, and she copies the effects of nearly every badge you have equipped, letting her buff herself to high heaven if you came into the fight with your strongest badge setup; defensive badges in particular will let her stack obscene amounts of damage reduction and HP buffs (especially Armored, which makes her ImmuneToFlinching), greatly prolonging an already dangerous fight. Even carrying food (besides the Golden Carrot), Cocoa Bombs and ''EN'' is a bad idea, because she can even use ''those'' against you.

** The fairy duo Lilli and Pixie are a DualBoss notable for spending the whole fight airborne, forcing you to use your weaker magic attacks or risk getting hit to sneak in a few aerial attacks or Super Carrots. Unlike Syaro and [[spoiler:Miru]], the other bosses who harshly restrict your offensive options, they each have [[DamageSpongeBoss a massive amount of HP]] and no moments where their defenses are dropped, meaning that they won't go down quickly no matter how you face them. Offensively, they use some of the most complex coordinated BulletHell in the entire game, a lot of which inflicts high damage and multiple painful debuffs, as well as certain aerial phases forcing you to manage awkward airborne movement while still dodging. Put all of this together, and you get an incredibly painful encounter that is both highly unforgiving and drags out for an absurdly long time. The only saving grace of the fight is that they'll periodically spawn enemies that heal you when you beat them, although they themselves are also liable to do more damage if you aren't careful.

** The fairy duo Lilli and Pixie are a DualBoss notable for spending the whole fight airborne, forcing you to use your weaker magic attacks or risk getting hit to sneak in a few aerial attacks or Super Carrots. Unlike Syaro and [[spoiler:Miru]], the other bosses who harshly restrict your offensive options, they each have [[DamageSpongeBoss a massive amount of HP]] to make defeating them a chore and no moments where their defenses are dropped. Offensively, they use some of the most complex coordinated BulletHell in the entire game, a lot of which inflicts high damage and multiple painful debuffs, as well as certain aerial phases forcing you to manage awkward airborne movement while still dodging. Put all of this together, and you get an incredibly painful encounter that is both highly unforgiving and drags out for an absurdly long time. The only saving grace of the fight is that they'll periodically spawn enemies that heal you when you beat them, although they themselves are also liable to do more damage if you aren't careful.

** Pandora from the Golden Pyramid deserves a mention for using a wide variety of attacks that generally require some unorthodox thinking to get around, as well as spending most of her battle in the air, forcing you to rely mostly on Ribbon's ranged attacks. The real key to beating her is micromanaging your SP meter so that you can hit her with Erina's hammer combos during the brief time she's on the ground. Add in the fact that she's the boss of ThatOneLevel, and that leaving her chamber to grab more items will force you to retrace your steps through a long corridor filled with [[ScrappyMechanic searchlights you have to wait to pass over]] on the return journey, and you have the perfect recipe for ThatOneBoss. Not to mention, there's an Illusion Pandora in the bottom of the Pyramid that guards the Chaos Rod, who has higher stats, even more unconventionally difficult attacks, and the ability to put up a chaos field at low health that slows you to a crawl when you're anywhere within a generous radius, making it borderline impossible to finish her with melee attacks. [[ThisIsGonnaSuck Good luck fighting her, you will need it.]]
** [[spoiler:Miriam]] is the only boss that actively punishes you for completion (beyond the normal LevelScaling), as nearly every power-up you own adds to her list of very difficult moves, and she copies the effects of nearly every badge you have equipped, letting her buff herself to high heaven if you came into the fight with your strongest badge setup; defensive badges in particular will let her stack obscene amounts of damage reduction and HP buffs, greatly prolonging an already dangerous fight. Even carrying food (besides the Golden Carrot) and Cocoa Bombs is a bad idea, because she can even use ''those'' against you.

* SugarWiki/FunnyMoments: Erina's first encounter with Ribbon results in a boss fight due to Ribbon being afraid that Erina wants to eat her. The BonusBoss encounter with Ribbon starts with the exact same premise, only this time [[spoiler: after winning, it's implied that Erina actually ''does'' eat Ribbon.]]

** The Hall Of Memories, which forces you into a lengthy gauntlet consisting of a mishmash of every level in the game, alongside [[DegradedBoss degraded versions of every boss in the game]]. Even with a fraction of their moveset and lower HP, every illusion boss is still absolutely brutal due to the sheer amount of damage they do in this level, and the fact that they're surrounded by rank and file enemies that ''also'' do a ton of damage makes the boss patterns harder to dodge. In fact, it's outright recommended to just try and skip past them to take minimal damage.

** Illusion Alius IV, [[spoiler:the last boss encountered during the BossRush in Forgotten Cave II]]. While you have a full arsenal by now, she has another trick up on her sleeve. Her attacks can cause Unstable, a status effect that will increase or decrease your speed at complete random, making controlling yourself almost nigh-impossible. She will then take advantage of your current state to hit you with her hammer for around 500+ damage (While your HP should be at around 1000).

** [[spoiler:Miriam]] is the only boss that actively punishes you for completion (beyond the normal LevelScaling), as every single power-up you own adds to her list of very difficult moves, and she copies the effects of nearly every badge you have equipped, letting her buff herself to high heaven if you came into the fight with your strongest badge setup; defensive badges in particular will let her stack obscene amounts of damage reduction and HP buffs, greatly prolonging an already dangerous fight. Even carrying food (besides the Golden Carrot) and Cocoa Bombs is a bad idea, because she can even use ''those'' against you.

** The Chaos Rod's boost effect has Ribbon fire rapid shotgun-spreads of exploding orbs that Curse. Normally pretty standard, but planting Ribbon right on top of an enemy and activating the Boost deals an obscene amount of damage, ripping through most bosses in seconds. It helps that a lot of bosses love to hover at just the right height for Ribbon to sit on top of while using said Boost if you position yourself right under them before you do it.

** Any of the Dodge Master achievements (which require you to pull off a NoDamageRun against specific bosses, which have to be at least level 50 for them to count), but especially [[spoiler:Noah]], since you have to kill her first and second form without getting hit twice, and [[spoiler:Irisu]], due to the [[MarathonBoss sheer length]] of her fight. Notably [[spoiler: Noah+, her final form which has its own seperate Dodge Master achievement]] is relatively easier. Worse, the bosses' attacks are not always telegraphed well and are semi-randomized in order[[note]]...outside of Miru, Miriam, and Irisu, who use entirely fixed patterns[[/note]], meaning that the achievement borders on being luck-based at times. The game will give you some leeway against bosses starting from [[spoiler:Miru]] onward, allowing you to take at least 1-3 hits before failing the achievement. [[MarathonBoss But then again...]]

** Illusion Alius' counterattack. She has a vicious counter attack that can take out half your health ''at the very least'' if you melee attack her while she has "[[VisibleSilence ...]]" above her head. The problem is that her battle is very fast paced so that it's unlikely you'll noticed it, and she can do this '''[[TheComputerIsACheatingBastard even if she's stunned]].''' A very careful approach and Hit-and-Run tactic is needed to avoid her counterattack.

** [[spoiler:Irisu]] can also put a debuff on you called [[ExactlyWhatItSaysOnTheTin Instant Death]], which causes the next attack that hits you to do [[FourIsDeath 4444]] damage. There are a few ways to get it, the most notable way being to do over 300 damage with one hit when she has the "300 Revenge" status. Did you [[DamnYouMuscleMemory accidentally]] Bunny Strike her? Cue the [[SoundCodedForYourConvenience super-slowed-down music]]!

** The Cyber Flower, which continues Boost Attacks until both your Boost and Mana meters are drained. Pick up enough mana upgrades, and this means you can trigger a Boost Attack that lasts even longer than a Max Boost Attack with only half the Boost Meter, making the Max Bracelet redundant. Naturally, you only get this just before the TrueFinalBoss. [[spoiler:If you do some difficult sequence breaking in the System Interior, you can actually get this as early as ''Chapter 3.'']]

** The first 3 Special battles against Ribbon, Cocoa, and Ashuri are particularly infuriating, mostly because of the brutal debuffs the bosses slap you with on successful hits - and considering they're SP bosses, they're ''going'' to hit you. Ribbon isn't as bad, as she drains your Amulet and Boost meters, but Ashuri is far worse - not only does she have an annoying tendency to break out of combos and chain attacks together in ways that are effectively impossible to dodge, each of her attacks totally drains your MP and ''disables your badges'', along with occasionally reducing your movement speed and leaving you open for another hit. Cocoa is possibly the worst of them all, as all of her attacks inflict Mortality to strip you of your invincibility frames, letting her instantly kill you if you have a run-in with a dense cluster of bullets. And don't even dare trying to heal during the fight, because using healing items will both heal the bosses and [[TurnsRed piss them off]] - particularly noteworthy are SP Ribbon starting to deal ''quadrupled damage'', and SP Ashuri gaining [[AttackReflector 99 Reflect]] and [[OneHitKill 300 Revenge]] to effectively make you unable to attack her for the next while.

** Looking for more challenge? Try any of the special bosses from ''Before Next Adventure'', which take 4 existing bosses (three of which are on this list), dial their stats UpToEleven, and overhaul their fights to the point where they may as well be totally different bosses. Even if you choose their easier left-side path, you'll still probably have a bad time - and if you choose the right-side path (which increases their level and gives them buffs), or heaven forbid any of the [[HarderThanHard Extreme]] paths...[[ThisIsGonnaSuck good luck.]]
*** Sorceress of the Tundra Rita has an [[DamageSpongeBoss absolutely titanic amount of health]] and fires volumes of complex patterns that sometimes slap you with Freeze. Her gimmick is the snowflake bullets she spawns, which can be destroyed to dodge otherwise-unavoidable patterns - destroy enough, and she'll take a massive PercentDamageAttack and temporarily be hit with Zero Offense, making her deal ScratchDamage for a short time. Problem is that the requirement to trigger the damage bursts get increasingly high over the course of the fight, many of her attacks require unintuitive thinking to get the most mileage out of the snowflakes, and if the AIRoulette hates you, she sometimes won't even use snowflake attacks; and you'll need them, since none of your regular attacks will do enough damage to even put a dent in her. On top of all of this, once you take out most of her health, she uses "Before the Mysterious Disappearance" [[UnexpectedGameplayChange and forces you into an ascending platformer]] ''while'' still bombarding you.
*** Glitched Syaro Returns, like her regular variant, is immune to melee attacks. Unlike her regular variant, she not only starts with massive damage reduction that only wears down over time (forcing you to endure her grueling attacks for a significant amount of time), she's a BarrierChangeBoss who is only ever vulnerable to one type of magic at a time, making it even harder to hurt her. Offensively, she retains her volumes of missiles (which now fire one of three types of targeted lasers on impact depending on their color), and her BeamSpam is dialed UpToEleven, including several complex beam patterns and dash attacks that require some extremely unorthodox thinking to avoid consistently. On the plus side, she still takes increased damage from Carrot Bombs, but good luck lasting long enough for them to do anything through her armor.
*** Miru Syndrome, like her original version, deprives you of Ribbon, but that's the least of your worries. All of her BulletHell is dialed UpToEleven with incredibly difficult patterns, and she is now able to do massive damage right out of the gate instead of only starting to hurt at lower health, on top of giving you defensive debuffs. You won't be able to even harm her for the first chunk of the fight. Instead, you need to survive several fixed cycles of her grueling attacks, and brave three intermissions between them - two souped-up illusions of Cyber Noah with a beefed-up Illusion Alius between them, although Amulets deal massive damage to Miru herself if used on the intermission bosses. All of this will likely take ten minutes ''at the least'', during which your buffs will run out and you'll likely be gradually whittled down to nothing. In the last stage of the fight, you'll get Ribbon back and Miru will start taking significant damage, but she will also start to deal ''even more damage'', on top of having a periodic unavoidable attack guaranteed to shave off a few hundred HP at the least if the fight drags on long enough for her to use it.
*** Irisu in Wonderland takes everything that made Irisu hard and turns it UpToEleven. She's still able to spam you with lethal debuffs for certain attacks (including a particular attack later on that inflicts a guaranteed dose of Mortality if you don't I-frame through it), each individual bullet deals insane amounts of damage, and there are a '''[[BulletHell lot]]''' more of them now, compounded with many, ''many'' unconventional attacks that practically turn her into a PuzzleBoss at times if you don't want to take massive damage and die quickly. Since this is [[MarathonBoss Irisu]] we're talking about, she still takes a titanic amount of damage and can leech HP/MP/BP on hit, making the fight generally drag on for twenty minutes ''if you're lucky'' (although she mercifully loses her permanent AttackReflector in her third cycle). Even if you can weather her brutal attacks, she keeps her [[HoldTheLine endurance phase]], which is much faster but also ''far'' more intense. And just in case you want to rely on the charged Rainbow Egg, she ''steals most of your money'' at the start of the fight. The game notably [[SuspiciousVideoGameGenerosity gives you bursts of healing at certain health intervals]] - needless to say, you'll need every last bit of it.

** While enemies that use StandardStatusEffects are annoying in general, the green/purple UPRPRPC members who can inflict Poison are extremely dangerous due to how fast the debuff in question drains your HP at, especially on higher difficulties. On Hard and above, taking a single blow from one without the Tough Skin badge equipped will basically eat up your entire health bar, leaving you prey for other enemies if you can't heal yourself.

** Seana in her first fight is just as jumpy as Ashuri or the bear twins, and has the added advantage of being fought underwater where your movement is impaired, or outright neutered if you haven't picked up the Water Orb from Nieve first. It doesn't help that she can often shrug off hitstun if attacked when moving, spends most of her time floating and thus hard to hit, or using attacks that make it so you have to maneuver while floating, leaving you at the mercy of the water physics.

** The Hammer Roll item is tricky to use and is likely to be used by mistake, potentially sending you rolling to your doom since it can't be cancelled. However, a patch gave Hammer Roll a new combo with the rising attack that lets you cancel it, gives Erina a boost in her MP and SP recovery and allowed it (like other items) to be turned off.

** Basically any enemy that inflicts StandardStatusEffects, [[BulletHell saturates the screen with fast bullets]], or uses homing attacks, especially because unlike bosses they can attack in groups. The first example is particularly dangerous, especially the green/purple UPRPRPC members who can inflict Poison, which drains your HP at an alarming rate, especially on higher difficulties.

* GoddamnedBats: Most flying enemies fall into this category due to the difficulty of hitting them, especially if you don't have any of the aerial mobility upgrades or a homing/wide magic type yet. While the bee enemies in the starting areas at least dive-bomb you to give you a chance to fight back, the ranged card-symbol fairies and ''especially'' the blue bees in the Icy Summit (who hover at the very top of the screen and rain fire on you) aren't as kind.

* DemonicSpider: The [[spoiler:nerds/otaku]] in the Warp Destination/[[spoiler:Outside World]]. They respawn infinitely, are hard to stagger, have flash attacks that come out instantly and are hard to dodge, deal high damage, are one of the few enemies that never give health when defeated, and [[ArsonMurderAndJaywalking their sprite looks ugly as hell]]. And then, after their encounter, you have to deal with [[ThatOneBoss Illusion Alius]].

** Even for [[BonusBoss SP bosses]], the first 3 Special battles against Ribbon, Cocoa, and Ashuri are particularly infuriating, mostly because of the brutal debuffs the bosses slap you with on successful hits - and considering they're SP bosses, they're ''going'' to hit you. Ribbon isn't as bad, as she drains your Amulet and Boost meters, but Ashuri is far worse - not only does she have an annoying tendency to break out of combos and chain attacks together in ways that are effectively impossible to dodge, each of her attacks totally drains your MP and ''disables your badges'', along with occasionally reducing your movement speed and leaving you open for another hit. Cocoa is possibly the worst of them all, as all of her attacks inflict Mortality to strip you of your invincibility frames, letting her instantly kill you if you have a run-in with a dense cluster of bullets. And don't even dare trying to heal during the fight, because using healing items will both heal the bosses and [[TurnsRed piss them off]] - particularly noteworthy are SP Ribbon starting to deal ''quadrupled damage'', and SP Ashuri gaining [[AttackReflector 99 Reflect]] and [[OneHitKill 300 Revenge]] to effectively make you unable to attack her for the next while.
** While Saya is rather easy to beat, her 'Pillar' form in ''Is The Order a DLC'' is not. Her wind based attacks are much harder to dodge, come out far faster, and hit much harder, on top of many of them requiring unorthodox thinking to avoid. On top of this, her LimitBreak lasts ''much'' longer, and trying to use recovery items during the fight [[TurnsRed just pisses her off]]. She is basically a [[BonusBoss Special boss]], but unlike them, she's mandatory to beat to advance the story.

** The second fight with Ashuri certainly counts. Most bosses gain a Defense Boost+ buff that makes them NighInvulnerable when they reach a certain threshold of health. Once they reach this point, they go into their signature attack, and the Defense Boost+ buff vanishes. Ashuri does not roll this way. She gets the Defense Boost+ and then stalls as long as she can before doing her signature attack, and then ''keeps'' the buff until the entire attack is complete. Basically, she spends a ''very'' long time with the Defense Boost+ buff on top of her being incredibly mobile and jumpy ''before'' she gets the buff, making the entire fight a gigantic time waster. On higher difficulty levels, the first fight with Ashuri also counts for the same reasons. This is lampshaded in the achievement for getting Saya first, which itself calls Ashuri a time-waster.
** The twin bears Nieve and Nixie. Both bosses have the same issues. They can slap you with the freeze debuff, which deals damage to you if you use your hammer or other SP using attacks. Most annoyingly, however, they jump around a lot, making it difficult to hit with ranged attacks as well as maximizing the chance of them randomly slapping you for contact damage. Also, they use their attacks at a height that doesn't stop the combo meter, unlike most bosses, which requires you to use the Cashback badge or seeking attacks to maintain a combo, or risk jumping up and getting hit by their attacks.

** [[MirrorBoss Illusion Alius II]] comes soon after Chapter 3 begins and is hard primarily for two reasons: 1. It comes immediately after a MiniBoss battle with [[spoiler:the two flash-shooting nerds followed by a squad of more nerds who have less HP but are just as deadly, and [[DroughtLevelOfDoom with no heal points during this entire ordeal]].]] 2. Unlike its previous iteration, this boss now has access to some of your more advanced techniques, including the hammer combo. In a game where most of the bosses like to hang back and fire bullet hell at you, this chick just straight up bum rushes you with obscenely damaging melee strikes, and can combo you with her hammer for an obscene amount of damage (at ''least'' 200 HP if it all connects; you'll probably have around 250-300 HP depending on how many HP upgrades you've bought and found, for reference), which also stunlocks you and is liable to be a OneHitKill on the higher difficulties. Making matters worse is that she breaks out of staggers very quickly and her attacks all come out ''extremely'' quickly with effectively no telegraph, forcing you to play safe or risk Illusion Alius breaking out of your attack chain and immediately tearing you a new one. You'll either need to be very good at not getting hit, or have to reload to your last non-automatic save and do the whole barrage again without getting hit so as to maximize HP for this fight. Did we mention that every single one of her attacks slaps you with a debuff that reduces your attack and defense? After you beat her, you'll have to fight the mirror Ribbon, and it really says something when that's the ''much'' easier half of the battle.
** Illusion Alius III, who comes soon after Chapter 4 begins, also qualifies for much the same reasons. What makes her worse than the previous one is that she now has access to the air dash, and will use it completely out of nowhere with no warning whatsoever. And unlike ''your'' air dash, it's lightning fast and travels the length of the screen. She also has all the same tactics the previous version used. To make matters worse, before you can even get to her you have to deal with a ''much'' longer sequence full of [[spoiler: nerds]], including two MiniBoss battles with groups of them. Fortunately you do get to heal some health in the interim during the pre-fight with [[spoiler: Noah]], but it isn't much, and it relies on you not getting hit by ''her'' too! [[SarcasmMode Have fun!]]

** The second fight with Ashuri certainly counts. Most bosses gain a Defense Boost+ buff that makes them NighInvulnerable when they reach a certain threshold of health. Once they reach this point, they go into their signature attack, and the Defense Boost+ buff vanishes. Ashuri does not roll this way. She gets the Defense Boost+ and then stalls as long as she can before doing her signature attack, and then ''keeps'' the buff until the entire attack is complete. Basically, she spends a ''very'' long time with the Defense Boost+ buff on top of her being incredibly mobile and jumpy to begin with, making the entire fight a gigantic time waster. On higher difficulty levels, the first fight with Ashuri also counts for the same reasons. This is lampshaded in the achievement for getting Saya first, which itself calls Ashuri a time-waster.

* AudienceAlienatingPremise: The heavily {{Moe}} artstyle, some of the more [[{{Stripperific}} questionable]] [[{{Fanservice}} character designs]] (particularly for characters that look on the younger side, like Ribbon), and the mere idea that the game revolves around a PlayboyBunny beating things with a hammer have disconcerted quite a few would-be players, even those fond of Metroidvanias.

* DemonicSpider: The [[spoiler:nerds/otaku]] in the Warp Destination/[[spoiler:Outside World]]. They respawn infinitely, are hard to stagger, have flash attacks that come out instantly and are hard to dodge, deal high damage, are one of the few enemies that never gives health when defeated, and [[ArsonMurderAndJaywalking their sprite looks ugly as hell]]. And then, after their encounter, you have to deal with [[ThatOneBoss Illusion Alius]].

** The second fight with Ashuri certainly counts. Most bosses gain a Defense Boost+ buff that makes them nigh invulnerable when they reach a certain threshold of health. Once they reach this point, they go into their signature attack, and the Defense Boost+ buff vanishes. Ashuri does not roll this way. She gets the Defense Boost+ and then stalls as long as she can before doing her signature attack, and then ''keeps'' the buff until the entire attack is complete. Basically, she spends a ''very'' long time with the Defense Boost+ buff on top of her being incredibly mobile and jumpy, making the entire fight a gigantic time waster. On higher difficulty levels, the first fight with Ashuri also counts for the same reasons. This is lampshaded in the achievement for getting Saya first, which itself calls Ashuri a time-waster.

** [[spoiler:Miriam]] is the only boss that actively punishes you for completion (beyond the normal "bosses level up as you do" thing), as every single power-up you own adds to her list of very difficult moves, and she copies the effects of nearly every badge you have equipped, letting her buff herself to high heaven if you came into the fight with your strongest badge setup. Even carrying food and Cocoa Bombs is a bad idea, because she can even use ''those'' against you.

** The Hammer Roll item is tricky to use and is likely to be used by mistake, potentially sending you rolling to your doom. However, a patch gave Hammer Roll a new combo with the rising attack that gives Erina a boost in her MP and SP recovery and allowed it (like other items) to be turned off.

** The Erina and Ribbon badges, which are only gotten after beating the TrueFinalBoss. On top of providing a wide array of general buffs (10% damage reduction and +20% item effectiveness for the former, and -15% MP usage for the latter), one lets you continue Erina's hammer twirl for as long as you have SP to fuel it, and another lets you spam charge attacks for as long as you have mana. Both are incredibly powerful techniques (the first one is especially good for stunlocking enemies while Ribbon boost attacks them.)

** Lilith's second phase is surprisingly forgiving, especially compared to her [[NintendoHard first phase]], for various reasons. First, you need to initiate her second phase yourself, which means you can save your game and warp back to [[PlayerHeadquarters Rabi Ribi Town]] to buy more items before fighting her. Secondly, you fight her in [[UnexpectedGameplayChange an air battle reminiscent of a shoot-em-up game]] which gives you free movement range. Thirdly, Erina's hitbox is noticeably small, with most bullets going right through her. Finally, your bullets home in on Lilith which means you don't even need to properly position yourself to damage her.

** The second fight with Ashuri certainly counts. Most bosses gain a Defense Boost+ buff that makes them nigh invulnerable when they reach a certain threshold of health. Once they reach this point, they go into their signature attack, and the Defense Boost+ buff vanishes. Ashuri does not roll this way. She gets the Defense Boost+ and then stalls as long as she can before doing her signature attack, and then ''keeps'' the buff until the entire attack is complete. Basically, she spends a ''very'' long time with the Defense Boost+ buff, making the entire fight a gigantic time waster. On higher difficulty levels, the first fight with Ashuri also counts for the same reasons. This is lampshaded in the achievement for getting Saya first, which itself calls Ashuri a time-waster.

* AudienceAlienatingPremise: The heavily {{Moe}} artstyle, some of the more [[{{Stripperific}} questionable]] [[{{Fanservice}} character designs]] (particularly for characters [[{{Squick}} that look on the younger side]] like Ribbon), and the mere idea that the game revolves around a PlayboyBunny beating things with a hammer have disconcerted quite a few would-be players, even those fond of Metroidvanias.

** Any of the Illusion Alius's hammer combos, as detailed below.

** [[spoiler:Miriam]] is the only boss that actively punishes you for completion (beyond the normal "bosses level up as you do" thing,) as every single power-up adds to her list of very difficult moves, and she copies the effects of every badge you have equipped, letting her buff herself to high heaven if you came into the fight with your strongest badge setup. Even carrying food and Cocoa Bombs is a bad idea, because she can even use ''those'' against you.

** The Hall Of Memories, which forces you into a lengthy gauntlet filled with [[DegradedBoss degraded versions of every boss in the game]]. Even with a fraction of their moveset and lower HP, every illusion boss is still absolutely brutal due to the sheer amount of damage they do in this level, and the fact that they're surrounded by rank and file enemies that ''also'' do a ton of damage makes the boss patterns harder to dodge. In fact, it's outright recommended to just try and skip past them to take minimal damage.

** The Egg Launcher. It appears right next to the standard projectile weapon on the list. It's at the edge so it's harder to accidentally switch to it except its icon looks similar the one beside it. It's really strong if you have all the easter eggs but, if you fire one charged shot with it, you lose all of your MP. Even after a patch allowed the player to turn off items, this ''still'' can't be removed from the RingMenu because it does not occupy space in the item list.

*** Sorceress of the Tundra Rita has an [[DamageSpongeBoss absolutely titanic amount of health]] and fires volumes of complex patterns that sometimes slap you with Freeze. Her gimmick is the snowflake bullets she spawns, which can be destroyed to dodge otherwise-unavoidable patterns - destroy enough, and she'll take a massive PercentDamageAttack and temporarily be hit wit Zero Offense, making her deal ScratchDamage for a short time. Problem is that the requirement to trigger the damage bursts get increasingly high over the course of the fight, many of her attacks require unintuitive thinking to get the most mileage out of the snowflakes, and if the AIRoulette hates you, she sometimes won't even use snowflake attacks; and you'll need them, since none of your regular attacks will do enough damage to even put a dent in her. On top of all of this, once you take out most of her health, she uses "Before the Mysterious Disappearance" [[UnexpectedGameplayChange and forces you into an ascending platformer ''while'' still bombarding you.]]

* GameBreaker: From Chapter 6 onward, shelling out 25k to [[spoiler: Miru]] will get you every temporary buff in the game. Do this right before a boss fight and steamroll right over them...unless you're on a high difficulty or doing some of the strongest endgame encounters, upon which they become [[NintentoHard almost required.]]