History YMMV / RabiRibi

* 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.
** The Erina and Ribbon badges, which are only gotten after beating the TrueFinalBoss. On top of general SP and Mana buffs, 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.)
** 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, and with only half the Boost Meter. 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.'']]

*** 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 RandomNumberGod 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 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.

*** 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), and 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.

** 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, 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...]]

*** 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 massive damage that pierces her massive health bar and temporarily makes her deal ScratchDamage. 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 RandomNumberGod 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 health bar. 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.]]

*** 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), and each individual bullet deals insane amounts of damage, and there are [[BulletHell a '''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.

** 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. Oh, did we mention there is an Illusion Pandora in the lower sections of the Pyramid, who is even stronger? And that Illusion Pandora has multiple attacks that are essentially ''impossible to dodge''? And that she has far more health than the regular version? [[ThisIsGonnaSuck Good luck fighting her, you will need it.]]

** Syaro is encountered in the [[spoiler:System Interior]] within the same chapter, and like all other enemies in the area, she is [[NoSell immune]] to melee attacks, forcing you to use your weaker ranged attacks or specials to damage her. It doesn't help that she loves spamming strongly homing missiles, has a surprisingly fast WaveMotionGun that can catch you off guard if you're not watching her, and frequently goes invincible in the second half of the fight.

** [[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 unless you break into the secret [=CreSpirit=] base]].]] 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.

*** "Another Layer of Nightmare", which requires you to defeat SP Miru on Extreme+. Not only is it [[GuideDangIt not even explained how to fight a BNA boss on Extreme+]][[note]]Using a Cocoa bomb while the game is asking you to choose left (normal) or right (hard) difficulty will set the difficulty to Extreme, and doing this just as the difficulty is "locked in" at the end of the sequence will trigger Extreme+)]], while triggering an Extreme BNA boss is required for another achievement (which does give you a vague hint on how to do it), Another Layer of Nightmare actually needs you to ''beat'' SP Miru in this state, which will inflate her level to an absurd degree while giving her an obscene amount of stacking buffs.

** Any of the no damage achievements (the bosses 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. Notably [[spoiler: Noah+, her final form which is its own seperate achievement]] is relatively easier. Worse, the bosses' attacks are not always telegraphed well and are semi-randomized in order, 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...]]
** Taking out the SP bosses is already quite hard, but ''Before Next Adventure'' adds achievements that need you to defeat SP Rita, Syaro, Miru, and Irisu at Level 500 or above. At this level, every one of their attacks will deal ludicrous damage regardless of difficulty, and they'll have enough health to drag on the fight for well over 15 minutes each, maximizing your chances of slipping up and taking massive damage for your mistake.

** 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. She is basically a [[BonusBoss SPECIAL]] boss.

** 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, every boss is still absolutely brutal due to the sheer amount of damage they do at this point, and the fact that they're surrounded by rank and file enemies that ''also'' do a ton of damage and make the boss patterns harder to dodge.

** The deepest part of the Hall of Memories in the final chapter of ''Is the Order a [=DLC=]?''. It's bad enough that the area is loaded with spikes, lasers, and traps, some of which require some unconventional thinking to get around. But the worst part of the area is that ''you lose the Bunny Amulet as soon as you enter!'' And you won't get it back until just before you reach the final boss.

** The Floating Library is a PlatformHell absolutely riddled with spikes that deal OneHitKill amounts of damage, and can only be navigated through a series of difficult platforming challenges that require incredibly precise jumping and mastery of every movement tech in your arsenal to complete - and whatever rooms that don't have platforming will be staffed by crystal enemies that fire volumes of bullets and deal massive damage. To make matters worse, there are several items hidden here that require you to brave ''even tougher'' platforming than the rest of the Library. And the kicker is that since the Library is the last area before [[spoiler:[[TrueFinalBoss Iri]][[ThatOneBoss su]]]], there's a fair chance that whatever buffs and/or items you tried to bring will expire by the time you get through the spike mazes unless you've mastered the layout. And woe betide you if you're doing a [[SelfImposedChallenge no spike run]].

** [[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 all-female cast, BulletHell elements (complete with special {{Desperation Attack}}s,) and similar character designs (the most obvious one being Erina looking like Reisen with different-colored eyes and a PlayboyBunny outfit) have led to more than a few observations that this is basically a ''VideoGame/TouhouProject'' fangame with the SerialNumbersFiledOff.

** 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, and with only half the Boost Meter. Naturally, you only get this just before the TrueFinalBoss. [[spoiler:If you either do a difficult sequence break to skip to System Interior II, or use a hidden pathway in the System Interior, you can actually get this as early as ''Chapter 3.'']]

** 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, and with only half the Boost Meter. Naturally, you only get this just before the TrueFinalBoss, [[spoiler:unless you perform a difficult sequence break ''and'' beat the subsequent PlatformHell in System Interior II, in which case you can get it as early as ''Chapter 3'']].

** Illusion Alius' counterattack. She has a vicious counter attack that can takes out half your health 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.
** One of Lilith's attacks has her throwing hearts at Erina that have some tracking capabilities. If any of them hit Erina, they stun her. Lilith then walks up to Erina and the screen fades to black while Lilith does...''something'' to her, hitting her three times for 69 points of damage each. What makes it ThatOneAttack is that it is one of the very few attacks in the entire game that isn't scaled to your level; it will do 207 damage total to you no matter what. In a low percent run, this is essentially a OneHitKill.

** [[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 unless you break into the secret [=CreSpirit=] base]]. 2. Unlike its previous iteration, this boss now has access to the hammer. 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 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). 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 [[spoiler:nerds]] 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.

** Pandora from the Golden Pyramid deserves a mention for 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. Oh, did we mention there is an Illusion Pandora in the lower sections of the Pyramid, who is even stronger? And that Illusion Pandora has multiple attacks that are essentially ''impossible to dodge''? And that she has far more health than the regular version? [[ThisIsGonnaSuck Good luck fighting her, you will need it.]]

** Taking out the SP bosses is already quite hard, but ''Before Next Adventure'' adds achievements that need you to defeat SP Rita, Syaro, Miru, and Irisu at Level 500 or above. At this level, every one of their attacks will deal ludicrous damage regardless of difficulty, and they'll have enough health to

** 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, and with only half the Boost Meter. Naturally, you only get this just before the TrueFinalBoss.

* ThatOneAchievement: Any of the no damage achievements (the bosses 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. Notably [[spoiler: Noah+, her final form which is its own seperate achievement]] is relatively easier. Worse, the bosses' attacks are not always telegraphed well and are semi-randomized in order, 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...]]

** 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 temporarily stops boosts and drains a bit of the Bunny Amulet, 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.

** 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 temporarily stops boosts and drains a bit of the Bunny Amulet, 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 get a clean hit off. 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.

** [[spoiler:Irisu]]'s ''opening attack'' is a sequential barrage of screen-spanning shockwaves that inflict some absolutely brutal debuffs, the last of which is Instant Death (see below). It's hard to see coming unless you know about it beforehand, cannot be dodged, will basically result in an instant loss if you get hit, and essentially needs you to fire all of your Bunny Amulet charges and possibly a well-timed Super Carrot to avoid all of them. On Hard and above, the first wave will inflict Mortality, which removes your MercyInvincibility and guarantees that all the other rings will hit you too, Bunny Amulet be damned.

** [[spoiler: Irisu]] can 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]]!

** [[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 the hammer. 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 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). 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 [[spoiler:nerds]] 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.

** Syaro is encountered in the [[spoiler:System Interior]] within the same chapter, and like all other enemies in the area, she is [[NoSell immune]] to melee attacks, forcing you to use your weaker ranged attacks to damage her.

** While Saya is rather easy to beat, her 'Pillar' form in ''Is The Order a DLC'' is not. Her wind based attacks is much harder to dodge and hits much harder. She is basically a [[BonusBoss SPECIAL]] boss.
** [[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 moves, and she copies the effects of every badge you have. Even carrying food is a bad idea, because she can use ''that'' against you.

* HilariousInHindsight: ''VideoGame/AstralChain'' would later introduce another FinalBoss named [[spoiler:Noah]] with multiple forms, whose defeat is required to unlock a slew of PostEndGameContent, and who is engaged on [[spoiler:the roof of a hospital]].

* 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.

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

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