Many an installment of the controller-breakingly popular Final Fantasy series has its own lot of optional content, including extremely tough secret boss battles.
- Final Fantasy:
- There is a special secret random encounter that can only be met on the walkway heading towards Tiamat. It is named the Death Machine/Warmech and has damage capabilities surpassing Tiamat and Chaos. It also heals 5% of its health every turn.
- The Dawn of Souls remake for the GBA included optional dungeons with bosses from III, IV, V, and VI; only Omega and Shinryu from V were much harder than the regular Final Boss.
- The PSP remake ups the ante with Chronodia, who has eight forms. It's not a Sequential Boss, though; which one you fight depends on how you did in the Bonus Dungeon prior to fighting her. Either way, she's pretty hard.
- Final Fantasy II:
- The Infinity-1 Weapons and strongest armors are stored in chests in the final dungeons, guarded by powerful monsters. The Soul of Rebirth bonus mode also has Ultima Weapon, which grants the Ultima spell to Minwu upon defeat.
- The 20th Anniversary Edition has a sideplot revolving around the character of Deumion the guardian. It includes two new superbosses at the end of the Arcane Labyrinth. One is Phrekyos: a badass-looking Hell Hound summoned forth by Deumion to test your strength. It's both a capable mage and a hard hitter. The second is Deumion himself, but only in case you wish to get the Useless Useful Spell Destroy that he guards with his life. Deumion's not really hard, but he's got more HP than any other enemy in the game and can cast the Dark Emperor's Starfall spell, among others.
- Final Fantasy III: The DS and later versions have the Iron Giant, a beast with massively high defense, powerful physical attacks that cause a wide variety of Status Effects, the Meteor spell, and who gets four attacks per round. After you've depleted enough of his HP, his regular attack gets replaced with one that does double damage and hits all party members at once. Have fun!
- Final Fantasy IV:
- There are four optional bosses that become Eidolons once you beat them: Asura, Leviathan, Odin, and Bahamut. Only one of these is particularly difficult. The others require very specific strategies rather than a high-leveled party to defeat, making them closer to Puzzle Bosses than anything else. This is fitting, as the battles are intended to be tests of your skill.
- Several powerful weapons and armor in the final dungeon are guarded by horribly powerful Palette Swap bosses, including one that hits the entire party with unavoidable Doom when the fight starts (giving you a time limit before Total Party Kill).
- The GBA version added the Lunar Ruins Bonus Dungeon. It has trial rooms that can only be unlocked if its corresponding character is in your party during the Final Boss battle. At the end of each trial is a Lunar version of Rydia's Summons. Near the end of the dungeon is Brachioraidos, a dragon tough enough relative to the enemies found in the dungeon, and finally "Easytype" Zeromus at the very end.
- The DS remake removed most of those added by the GBA version, but features two new optional bosses only accessible through New Game Plus: Geryon, an amalgamation of the Four Elemental Archfiends found within the Giant of Babil, and Proto-Babil, accessed by bringing Dark Matter (stolen from Zeromus in a previous playthrough) to a rock face on the moon.
- Final Fantasy IV: The After Years features the return of Omega and Shinryu in the final dungeon, as well as Deathgaze and Ultima Weapon. The PSP version adds Lost Babil, a humungous mecha that requires a completed file and three parties to fight: one for the lower body, one for the upper body, and one for the inner CPU, which can be repeated indefinitely for Soma Drops and Silver Apples. The PC version removes the crossover bosses and adds back some of the bonus bosses from IV Advance, including Lunar Odin, Lunar Leviathan, and Lunar Bahamut.
- Final Fantasy V:
- Omega and Shinryu, who gave trinkets praising your deed upon death, although they are not that much tougher than Neo Exdeath in comparison. They would later make appearances in future games.
- V Advance was especially brutal with these, creating a Bonus Dungeon full of them. This included such opponents as Enuo, the original creator of The Void, which was the MacGuffin that was Exdeath's entire goal, and something that he couldn't control in the end; Omega MK. II and Neo Shinryu, are slightly upgraded versions of the ones from the original game.
- Final Fantasy VI: Mainly limited to the Advance remake.
- Three new espers: Leviathan, Gigantuar, and Gilgamesh.
- There are also five bosses found wandering in a pit within the Dragon's Den — Dark Behemoth, Abyss Worm, Gargantua, Earth Eater, and the Malboro Menaces and bosses-in-chests: Neslug, Plague, and the Flan Princesses, which use massive recovery, Doom to all, and Berserk to all, respectively.
- Kaiser Dragon was Dummied Out of the original game and, due to having an associated monologue, seems to have been intended to have been a bonus boss in the original version, but to have been cut for time. To even get to him the party must fight upgraded versions of the Eight Dragons, each much stronger than other bosses in the game.
- If Kaiser Dragon isn't enough for you, you can go through the Dragon's Den again and fight Omega Weapon, who is even tougher although with much less HP.
- Final Fantasy VII:
- Ruby Weapon and Emerald Weapon are added in the international version. Meanwhile, Ultima Weapon is a storyline boss, but it can be fought a few more times (via chasing it with the airship), with Cloud's Infinity +1 Sword as a reward for finally defeating it.
- Crisis Core has Minerva. Genesis's best form is nothing compared to her.
- Final Fantasy VII Remake:
- The first one involves completing all of Chadley's reports for the right to challenge Bahamut for his summon materia.
- Completing all of the Wall Market Colosseum battles and Shinra VR battles, especially on Hard mode, allows you to go through a gauntlet of all the summon bosses to face the Pride and Joy Prototype, an Early-Bird Cameo of the Proudclod boss fought near the end of the original game's Disc 2. Even worse, you can only do this challenge on Hard.
- In the Intergrade Updated Re-release, completing the INTERmission storyline allows Yuffie and Sonon to battle Pride and Joy Mk 0.5 in the VR simulator and allows Cloud and his companions to fight Weiss the Immaculate, the game's true ultimate enemy.
- Final Fantasy VII Rebirth: At the end of the protorelic quest line, you fight Gilgamesh, who wasn't present in the original. The boss can be challenged in any difficulty, but victory allows for an even tougher VR rematch in Hard mode.
- Final Fantasy VIII:
- Ultima Weapon is found in the Deep Sea Research Center following a (rather obtuse) puzzle. He has strong attacks, including the One-Hit KO Light Pillar, and is quite fast, to the point that a party with poor Speed junctions is at great risk of being wiped out by sequential attacks before they can recover. Fighting him allows you to Draw the Eden GF, and if you're really well prepared, you can also stock up on Ultima spells before finishing him off.
- Omega Weapon is found in Ultimecia's Castle, following another rather obtuse puzzle. His attacks are even stronger than Ultima Weapon's, allowing him to devastate an unprepared player, but once you know what to expect (and how to counter it), he's actually less challenging, as he attacks in a fixed pattern and is much slower than his counterpart, allowing you plenty of time to prepare for each of his moves, or failing that, just abuse your Limit Breaks to blitz him down before he gets around to the really bad stuff. Beating him gives you a Cosmetic Award on your menu screen, called "Proof Of Omega".
- Final Fantasy IX:
- Ozma, unique in that his difficulty has little to do with inflated stats and almost everything to do with proper strategizing, albeit with more than a hint of Guide Dang It!.
- Hades is complementary — He turns out to be a legendary synthesist, and one of the rewards for beating Ozma is something you can synth off to obtain Ark, the ridiculously over-the-top summon.
- The Tantarian, whose difficulty is based on strategy rather than just stats. Beating him nets an accessory that teaches the very useful Auto-Haste ability.
- Quina's master Quale can be fought once you catch 99 frogs in the Qu's Marshes, and his HP actually surpasses that of Ozma.
- Final Fantasy X:
- Ultima Weapon and Omega Weapon once again show up here, but they are not as powerful as some of the Monster Arena creations, the toughest is a gold-colored Palette Swap of Ultima Weapon, Nemesis. Most of the creations start at six-digit HP when in the main game you only fight three enemies with that much HP, and they will use and abuse high-powered attacks and/or astronomical defenses or evasion, as well as several cases of breaking established game rules (For example, Fenrir has a One-Hit Kill attack that even Deathproof won't protect against and Neslug has a special variation of Regen that can restore five or even six digits' amount of HP per iteration when normal Regen only restores a few hundred at best) In the International/HD versions, Omega's difficulty is slightly increased.
- The Dark Aeons and Penance in the International/HD versions. Some of the Dark Aeons were required encounters if you want to backtrack to certain areas. Penance is entirely optional, and he's accordingly brutal...12 million HP, potent attacks that devastate an unprepared party, and supporting limbs that do even more fun damage.
- Final Fantasy X-2:
- The Via Infinito monsters, led by Paragon and Trema. Black Elementals with the ability to just use Ultima at 255 magic whenever it wants, Chac for bypassing stone status resistances or debuffing all stats by TEN with Heaven's Cataract or Concherer who isn't too bad but IS a brick wall of defense.
- The Experiment, a Machina the Machine Faction in Djose Temple are working on throughout the game, which can be upgraded with parts the player obtains from digging in the Bikanel Desert. It is completely optional, and you only have to fight it for two points in the 100% Completion: the Djose Temple Episode Complete, and the Annihilator Blue Bullet.
- Angra Mainyu, a gigantic snake-like Fiend slumbering in the Bikanel Desert. It can be encountered as early as Chapter 1 during digging sessions if the player is unlucky, but to actually fight it in a proper battle, the player must complete a long sidequest first, one that begins in Chapter 3 and can only be concluded in Chapter 5.
- The Fiend Arena in the International/HD re-release has quite some nasty customers in their tournaments. Expect daunting foes like Trema and Paragon, Bahamut with over 100,000 HP and a sure-hit kill attack for 9999 damage per girl (all used at leisure), enhanced human enemies (Baralai, Nooj, Gippal, etc.) with jacked up stats and brand new cheapo moves to annihilate before a chance is had. The toughest of them all are Almighty Shinra, with potent spells meant to decimate the party right off the bat, and Major Numerus, a four-headed serpent with tons of abilities to decimate the characters. It's required to fight him with three Iron Dukes equipped (one girl apiece) or else you're just wasting your time.
- There are also three difficult opponents for the Sphere Break mini-game, the first of which gets unlocked by capturing the Varan enemy via the Creature Creator and raising it until it completes its Fiend Tale.
- Final Fantasy XII:
- Behemoth King, the eight non-story line Espers (which includes Zodiark), etc.
- Hell Wyrm, Omega Mk. XII, and Yiazmat. The last one is the boss with the most HP in the franchise (a grand total of 50 million), and can take multiple hours to defeat.
- The final battle in the bonus Trial Mode in the Zodiac version would pit the party against all five Judge Magisters at once.
- Final Fantasy Tactics A2: Upsilons A1 (leveled somewhere in the 60s) and A2 (Level 96), as well as the Level 99 mage clan.
- Final Fantasy XIII:
- Vercingetorix, boss of the final Mission. This bad boy has 15.8 million hitpoints and can't even be accessed until after you beat the game. But it's easier to beat by simply poisoning him and then guarding for the entire battle; this is because poison deals damage based on maximum HP, and Vercingetorix, as mentioned, has a lot of it.
- Long Guis also have even more HP, huge stats, and immunity to every form of status debuffs compared to Vercingetorix.
- Final Fantasy XIII-2:
- The Long Gui returns, and despite only having a quarter of the HP it had in XIII, it's still extremely tough to put down.
- Yomi is a weaker (but still formidable) version of Vercingetorix.
- Raspatil, a horrifyingly powerful Undying Cie'th that's probably the hardest fight in the vanilla game.
- The DLC Coliseum battles are all nasty, especially Jihl, the one person everyone who played XIII wanted to kill and Gilgamesh, who has almost 10 million HP and can heal himself. The most notorious monsters in the Coliseum, however, are Snow and Valfodr. First off, before you can fight Valfodr, you fight Snow, who has 10 million HP, and if you don't provoke him into attacking someone else and he continues to attack the same character for a set amount of time, he will use a Total Party Kill attack. Once you defeat him, you fight Valfodr, who has five increasingly difficult forms, progressively getting harder.
- Lightning Returns: Final Fantasy XIII: In the first playthrough you are capable of taking on the game's two superbosses, the Aeronite and Ereshkigal. Afterwards, if you go on to play Hard Mode, they can be fought again; their stats and health go through the roof, with Aeronite getting potentially 50 million HP.
- Final Fantasy XIV:
- 8-player Trials and Raids have a harder mode that's completely optional to do. For Trials, there's the Extreme version which rewards players with weapons and rare mounts. There's also the Unreal version for some Trials which is mostly the Extreme version, but adjusting the fight to the level cap. Raids have a harder Savage mode, which rewards players with the best equipment when said content is released.
- Then trumping Savage in difficulty is the Ultimate difficulty, which is this in Boss Rush form. With no checkpoints to save your sanity, this is the, well, ultimate test of coordination and skill. At the final stretch of the boss rush lies an exclusive form for the final boss it's themed after, which pulls out all the stops to ensure your party is hard-pressed to succeed. You have to complete the Savage raid at the time of its release to even attempt the fight in the first place.
- The Unending Coil of Bahamut sets the bar on what to expect as the first Ultimate raid, and it certainly doesn't disappoint. It consists of embellished and fiercer version of the final turn for each part of the Binding Coils of Bahamut (Turn 5, 9 and 13), with all of them pulling all their stops at the get-go compared to regular Coil, culminating with Bahamut Prime dropping a mini-Dalamud to the stage and sends powerful shockwaves that will wipe the party if not mitigated with a Limit Break from a tank-role player. And then after the Tera Flare phase, Bahamut Prime proceeds to unleash its inner rage in its golden form, and starts to spam Akh Morn and Exaflare, and if it was not defeated quickly it will begin to spam Morn Afah (appropriately means "eternal death" in dragon language) until the whole party is wiped out. Clearing the Unending Coil demands a great amount of team synergy and their proficiency with the battle mechanics much more than any other raids before it; at the time of its release, none of the participants were able to clear it within the first week, with the world first clear happens on the 11th day after the release.
- The Weapon's Refrain is also a gauntlet against several bosses in a row; Specifically: Garuda, Ifrit, Titan, Lahabrea, and the Ultima Weapon, the major bosses you encounter in A Realm Reborn. In addition to the moves they usually do being supercharged, the whole encounter is a giant puzzle, as the party needs to hit the Primals with their own attacks to power them up in order to obtain extra Limit Breaks for use against Lahabrea, and failing to do so will always result in a wipe. A Level 3 Caster Limit Break is required to destroy several self-destructing Magitek Bits before they explode, a Level 3 Healer Limit Break is needed to cleanse an otherwise uncleansable Doom debuff Lahabrea places on the party, a Level 3 Melee Limit Break is needed to finish off Lahabrea before he casts Dark IV to wipe the party, and a Level 3 Tank Limit Break is needed to survive the Ultima Weapon's opening attack of Ultima. Then, once the Ultima Weapon fight begins proper, dying to it causes it to build up its own Limit Break faster. If the Ultima Weapon reaches 100% charge, it begins dragging players one at a time into the air and blasting them with an attack that deals 999,999 damage and prevents their corpses from being targeted, in turn preventing them from being raised.
- The Epic of Alexander is boss rush for the Alexander raid series. The fight starts with the Living Liquid (the third Alexander raid), a boss infamous for being That One Boss when it was released, only this time the party must deal with all of its forms at the same time. The next phase is a Dual Boss against both Brute Justice (the eighth raid) and Cruise Chaser (the eleventh raid), while also dealing with the Judgement Nisi mechanic from the Manipulator (the fourth raid). Afterwards is a fight against Alexander Prime (the final raid), with assistance from the previous two bosses. For the final phase Alexander fuses with Brute Justice and Cruise Chaser in order to become Perfect Alexander, who can use its Time Master abilities to predict the party's future movements in order to determine how to best kill them. In order to counter this, the party must acquire the Enigma Codex from Shanoa (by executing a mechanic from the Alexander Prime phase correctly) so that they can see Alexander's predictions, allowing them to change their actions in order to counter Alexander's future attacks.
- The Dragonsong's Reprise is a retelling of Heavensward with a What If? twist. This raid starts off like a straightforward retelling of Heavensward, starting at The Vault (where the Knights of the Round are first fought and Haurchefant dies Taking the Bullet), then moves onto the fight with King Thordan, then with Nidhogg in Estinien's body, and finally with Nidhogg's eyes. Afterwards though, the party is taken back to the Vault where this time they must save Haurchefant from his canonical death by using a Level 3 Tank Limit Break to help him withstand the attack, and healing him so that he may survive long enough for the DPS to knock the spear of light that killed him away, all while dealing with the boss's Desperation Attack. By saving him, this leads into the Wandering Minstrel narrating the story to muse upon a potential alternate timeline that resulted from this Point of Divergence. First is King Thordan, who is now powerful enough to temper dragons, forcing the party to deal with them as well as his knights. At the end of this battle, the party must spare him when he begs for mercy, allowing him to get away to menace the heroes another day. Then the party must fight both Nidhogg and an enslaved Hraesvelgr, and the party must complete this stage without dying as well as juggle a timed AoE around the party or else one of the bosses gains a massive buff that will let them wipe the party. Finally, Thordan will claim the eyes of both Nidhogg and Hraesvelgr in order to become the Dragon-King Thordan, who becomes the final boss of the trial.
- The Omega Protocol is a fight against all of Omega's forms one after another. It first fights with its machine body from Alphascape V3.0, then its humanoid bodies from Alphascape v4.0, and then its "Reconfigured" form from the Savage version of V4.0. After it's seemingly defeated however, it forces itself to keep fighting even though its body is falling apart, and its determination to keep fighting allows it to harness the power of dynamis, resulting in the humanoid bodies getting a Golden Super Mode. During this phase, all party members must receive three stacks of the "Quickening Dynamis" buff by properly resolving the "Hello, World" debuffs that Omega inflicts throughout the phase. At the end of this phase, Omega fuses with Alpha, its reading of Alpha's thought processes allowing it to understand the Power of Friendship allowing it to become Alpha Omega. Assuming that the party properly acquired three stacks of "Quickening Dynamis", the buff transforms into "Brilliant Dynamis" and what follows can be best described as a Limit Break duel, with Omega spamming its own Limit Breaks one after another and the party responding in kind by using the Brilliant Dynamis buff to let every single party member use a Level 3 Limit Break.
- Memoria Misera is a very difficult boss. Based on a previous solo instance boss battle against Emperor Varis (or rather, a highly embellished version of him), much of the difficulty from the fight comes from mechanics that require precise synchronized placement of all party members to avoid stacking damage. As the fight moves into its second and third phases, a pair of DPS checks come into play as well, the first requiring both tanks to interacte with designated spots on the map to catch a massive sword beam and succeeding in the ensuing Active Time Maneuver to survive (emphasis on both tanks: if one of them is out of play, the other will quickly die and the party will wipe) while the party takes continuous damage, making it a taxing healer check as well. The second DPS check is accompanied by two attacks, one that requires the players to stack to mitigate damage and another that requires the players to spread out to avoid getting hit repeatedly. Each new phase also forces players to contend with more simultaneous mechanics going off. Any mistakes made in dealing with these mechanics can result in a Total Party Kill. Thankfully, the rewards for winning the fight are well worth it, consisting of high-end armor with five materia slots per piece.
- The Bozjan Southern Front contains three Duel Bosses (Gabriel, Beast King Lyon, and Sartauvoir the Inferno) that can only be fought by finishing an associated Critical Engagement without getting hit and getting selected for the duel in a roulette. Each one requires careful planning of Lost Actions to have any hope of success, and beating all three gives you the achievement title "Sword of the South." The duelling system returns in Zadnor, only this time the bosses have far greater HP to account for the Mettle sink buffs and powerful Lost Actions that were introduced alongside Zadnor.
- Both The Forbidden Land of Eureka and The Bozjan Southern Front have instances within them that offer a series of bosses to fight. These bosses can be no slouch either. For example, most of the bosses in The Delubrum Reginae in Bozjan will put a death countdown debuff on players if they fail mechanics twice. Note that all of these instances were designed for up to 24 players (though it technically can be entered with fewer). And unlike 24-man raids where it's more or less guaranteed to have 3 teams of 8 and designed with distinct "roles" for each (e.g., Team A does this, Team B does that), these instances don't have any such designation and players have to coordinate even more.
- Final Fantasy XV:
- There are three in the base version: The first is the Adamantoise, which is probably the largest boss in the series and also one of its longest encounters taking about 3 in game days, or 2 hours in real life to defeat. Beyond that is Naglfar and MA-X Angelus-0.
- Royal Edition added the recurring Omega as a Solheim superweapon forged to fell the Astrals. And surely enough, it was indeed impervious to attacks from them and conventional weapons. Only Royal Arms and top-tier Elemancy spells could do a dent against Omega, though the immunity switched from conventional weapons to Royal Arms whenever it Turns Red.
