A superboss is an optional boss that is very powerful, even more so than the game's final boss, and generally gives either large amounts of experience, rare items, or both. In the Final Fantasy series, they are usually found deep at the end of optional dungeons, or can only be found after a long series of sidequests. They normally have no bearing on the storyline, and their existence is rarely explained. Some superbosses even appear as regular, if rare, enemies, and can be fought repeatedly.
Likewise, the rewards gained from defeating a superboss are often not particularly useful—sometimes they give a key item as a proof of defeating the boss—as the player must already be extraordinarily skilled to defeat the boss in the first place, they thus have no need for further battle enhancements afterwards. Superbosses exist to challenge the player and give them something to do once the main storyline is finished.
The quintessential Final Fantasy superboss is Omega, a robot often implied to originate from an ancient civilization. Omega's counterpart or nemesis is said to be Shinryu, who also frequently appears as a superboss. Weapons are colossal monsters that have appeared as superbosses since their introduction in Final Fantasy VII.
Though actually only a very-rare random encounter, Warmech in the NES version can be considered a superboss, as its attacks are more powerful than the Four Fiends' combined. Its power has been toned down in remakes since Dawn of Souls.
Shinryu and Omega in the Lifespring Grotto, and Death Gaze in the Whisperwind Cove, are the superbosses that appear in the Dawn of Souls, the 20th Anniversary edition and mobile platform remakes based on the latter.
In the 20th Anniversary edition and remakes based on this version, Chronodia is an even stronger superboss, fought at the end of a new bonus dungeon.
In the 20th Anniversary edition and later versions based on the 20th Anniversary edition, Phrekyos is a superboss fought to gain each character's ultimate weapon. He can be fought an unlimited number of times, provided the player first clears each Arcane Labyrinth and does not kill Deumion. Deumion is also a superboss, and is the one who summons Phrekyos to test the player's skill. He uses the Starfall attack the Emperor uses in the final battle.
Prior to later remakes that added additional enemies, some random encounters could be considered superbosses in the same sense as the Warmech in Final Fantasy. The Iron Giant is a rare random encounter found in Pandemonium, and marks the creature's first appearance in the series. Four optional bosses, Astaroth, Beelzebub, Tiamat, and Zombie Borghen guard chests that contain powerful items.
In the Game Boy Advance and PlayStation Portable ports, the new Lunar Ruins dungeon is unlocked after beating the main game. "Lunar" versions of Rydia's Eidolons inhabit these caves. The actual superboss, Zeromus EG, lies at the end of the ruins. Another superboss, Brachioraidos, can be found on one of the ruins' lowest floors.
In the 3D remake versions, Geryon and Proto-Babil are the superbosses. Proto-Babil can be faced in New Game Plus after stealing the Dark Matter from Zeromus during the first playthrough, while Geryon is unlocked after beating the Elemental Archfiends in the Giant of Babil. Proto-Babil can be fought on the Moon's Surface, while Geryon can be fought either at the Giant of Babil or at Mount Ordeals.
Three superbosses are located in the Depths, including Omega and Lord Dragon (otherwise known as Shinryu) from Final Fantasy V, and the Ultima Weapon from Final Fantasy VI. They have some different attack patterns and abilities and the player obtains powerful equipment after defeating them.
Final Fantasy IV: The Complete Collection for the PlayStation Portable adds a new post-game boss called Lost Babil. The player must talk with Challengingway at the secret location on the True Moon to fight it. They must assemble three parties to fight three separate bosses, which consist of Lost Babil's torso, head and CPU. This could be seen as a reference or reappearance of previous superboss Proto-Babil.
Several of the lunar Eidolons—namely Lunar Dragon (who guards the Dualcast ability), Lunar Odin (who guards Ragnarok), Lunar Leviathan, and Lunar Bahamut—are exclusive superbosses for the mobile releases.
The original game included the first two superbosses to appear in the series, Omega and Shinryu. The Advance version adds stronger versions of these bosses, Omega Mk.II and Neo Shinryu, in the optional Sealed Temple dungeon. The final boss of the dungeon is also the final superboss, Enuo.
Kaiser Dragon was planned to be the superboss, but was dummied for unconfirmed reasons prior to the game's SNES release. Deathgaze acts as a sort of superboss, due to its end-game level of power, but its difficulty is diminished since the player is not intended to defeat it in a single encounter, but to weaken it over time.
In the Game Boy Advance and mobile/Steam ports, the Kaiser Dragon, a finished version of the dummied boss CzarDragon, awaits the player in the heart of the Dragons' Den after the player has defeated the eight legendary dragons found within. Once Kaiser Dragon has been defeated, the true superboss, Omega Weapon, will appear in its place.
The North American and following versions feature two powerful superbosses. The Emerald Weapon appears at the Bottom of the Sea at random locations, grants the player a key item that can be traded into (some of) the most powerful Materia in the game. The Ruby Weapon is found by making contact with its head as it is sticking out of the sand on the world map in the Corel Desert near the Gold Saucer, and grants the player a key item that can be traded into the game's most useful mount Chocobo.
Minerva is a superboss and the final mission of the Great Cavern of Wonders group, Mission 9-6-6. She has the highest HP of any opponent and uses some of the strongest attacks in the game. As the player can battle her repeatedly, the boss can be used for item and gil farming.
The Omega Weapon is fought at Ultimecia Castle, and Ultima Weapon is found at the bottom of the Deep Sea Research Center. Ultima Weapon is based on Ultimate Weapon from Final Fantasy VII, and even wields Cloud Strife's best sword, which was a drop from its counterpart in Final Fantasy VII.
Omega Weapon lies hidden in Ultimecia Castle, and to reveal it the player must ring the bell in the Art Gallery to have it appear out of the purple cloud in the chapel. Defeating Omega Weapon grants the player the Proof of Omega.
Ozma is found in the Chocobo's Air Garden after completing most of the Chocobo Hot and Cold sidequest. To hit it with Attack command, the friendly enemies must have been given their requested gem. Ozma is a large spherical entity that is released from an eidolon grave, giving credit to the idea it may be a forgotten eidolon that has thus lost its form. Ozma's unique attack pattern makes it especially difficult.
The International, PAL, and the HD Remaster versions include the Dark Aeons. Once they have been defeated, the strongest superboss, Penance, appears in the Calm Lands. The Weapons are also tougher in the newer versions, Omega Weapon significantly so, putting him on par with some of the Original creations at the Monster Arena.
The player can gain access to Via Infinito through Bevelle in Chapter 5 where many unsent characters became powerful fiends. The strongest opponent fought in the final floor is Trema, a former denizen of Yevon. Angra Mainyu in Bikanel Desert can be encountered multiple times during routine dig sessions, and can be fought and finally defeated after completing a quest in Chapter 5.
The International and HD Remaster versions includes the boss Major Numerus, a four-headed snake in another league relative to other superbosses. Although not quite as powerful, the fiend version of Shinra, titled Almighty Shinra, is also a superboss.
A few event bosses and High Notorious Monsters have been regarded as the most challenging encounters. This list has changed over the years, as the game evolves and new content influences the difficulty of older ones.
Of the High Notorious Monsters (HNMs) in Vana'diel, the reigning superboss used to be Absolute Virtue from Chains of Promathia. It was notorious for being undefeatable without using some form of exploit, as all prior successful methods of defeating it were patched out because it had not been killed the "proper way." Although it remained undefeated for years, within two months after the Level 80 cap raise, Absolute Virtue was finally defeated legitimately, but still poses a considerable challenge without the right alliance set-up.
Notable former HNM superbosses are Kirin, the first HNM that initially took nearly two hours to defeat, and Pandemonium Warden, which had its difficulty reduced due to it taking far too long to kill (a linkshell fighting for eighteen hours could not defeat it), an incident which generated a wave of bad press in gaming media.
Dynamis Lord, the final boss of Dynamis, was formerly the greatest event superboss. It initially required a minimum of forty players to defeat under a specific strategy (Red Mages using Chainspell Stun) which is still the main viable strategy used to defeat him to this day. Without this, the Dynamis Lord can annihilate entire alliances of players with a single use of its many special attacks, the most damaging of which is Oblivion Smash. Since the updates to the Dynamis system when the level cap was increased to 90, a revamped version known as Arch Dynamis Lord has been introduced.
Other battlefields known for their difficulty include "Divine Might," a battlefield that pits an alliance against the Ark Angels, "Waking the Beast," where one must face off against Carbuncle Prime and the six celestial avatars, as well as "The Wyrmkin Descends," which is a battlefield against the Wyrmking Bahamut and his wyrm minions.
Other notable bosses include Odin, the boss of Einherjar whom as Odin II is much stronger after the first time he is defeated as Odin I, and the Delve bosses Tojil, Dakuwaqa, Muyingwa, Cailimh, Wopket and Utkux. Today, only these along with the bosses of Legion and the High-Tier Battlefields on Very Difficult mode are unsoloable.
The Hell Wyrm can be fought in the Sochen Cave Palace after the conclusion of the Wyrm Philosopher sidequest. It is considered a mere prelude to the hardest superboss, Yiazmat. Yiazmat is an Elite Mark accessed after every other Rank VII Mark has been completed (except the Shadowseer). It is found at the Ridorana Cataract coliseum, and had the most HP of any enemy in the series until Lightning Returns: Final Fantasy XIII was released, weighing in at just over fifty million (50,112,254). Yiazmat takes several hours for the average player to kill. Later Marks can be considered superbosses due to their powerful and devastating attacks.
Omega Mark XII is a less time-consuming superboss that can be accessed once the Mark for Yiazmat has been accepted.
Yiazmat returns, sheltered within the dark confines of Midlight's Deep. Though not as powerful as its Final Fantasy XII incarnation, Yiazmat has gained the elemental affinity of lightning and has retained most of its devastating attacks. It is a Ranged unit.
Vercingetorix is the final Cie'th Stone mission. For his mission to become available, the player must have defeated Missions 27 to 51. Vercingetorix is a flying Undying with 15,840,000 HP. Defeating Vercingetorix, and as such completing all missions, earns the player the Galuf's Grail achievement/trophy and the Exorcist achievement/trophy for defeating the final Undying Cie'th.
Another superboss is Long Gui, a massive oretoise that becomes available once the player completes the fal'Cie Titan's trials, as well as missions 56–62, at which point every oretoise on the Archylte Steppe, except one, will become a Long Gui or a Shaolong Gui. Long Gui has 16,200,000 HP, while its two front legs have 1,080,000 HP each. Defeating Long Gui earns the player the Adamant Will achievement/trophy.
The two most powerful enemies in the Archylte Steppe could be considered superbosses: The Long Gui from Final Fantasy XIII returns with the highest HP. Another enemy, Yomi, is similar in appearance to, and uses the same battle tactics as, Vercingetorix from the original game. One of the Undying, it's a one-of-a-kind Cie'th. Defeating it along with the Long Gui, Ochu, and Immortal will award the player the Big Game Hunter achievement/trophy.
Raspatil is a superboss found on the Ashensand of Oerba in 400 AF. It boasts 3,666,000 HP and can call other powerful Cie'th into battle. Defeating her awards the player 25,000 CP (the most of any enemy) and the Fair Fighter achievement/trophy if the player defeated her in Normal Mode.
Other superbosses released as downloadable content may be fought at the Coliseum upon purchase. These battles (most notably Snow, Gilgamesh, and Valfodr) are much more difficult than any battle encountered in the game's regular content. Both Snow and Gilgamesh sport 9,999,999 HP, while Valfodr increases in difficulty each time he's defeated, starting at 5,172,000 HP at level 1 and ending at 15,516,000 at level 99 (and a "HALVED" resistance to all damage, effectively the same as if he had 31,032,000 HP), in his fifth incarnation. For a fully-leveled party, only the DLC superbosses will still pose a significant challenge.
Aeronite must be defeated to complete the "What Rough Beast Slouches" sidequest in the Dead Dunes. It appears as a "black hole" similar to rare enemies in Final Fantasy XIII-2 and moves around the Giant's Sandbox on a timed schedule. It boasts 11,000,000 HP on Normal Mode, which means 17,500,000 HP when encountered in a Chaos infusion or fought on the Ark, 38,500,000 HP on Hard Mode, and 57,750,000 HP on Hard Mode when encountered in a Chaos infusion or fought on the Ark, giving it the highest potential HP of any Final Fantasy boss to date.
Ereshkigal is encountered on the 33rd and final floor of the optional dungeon, the Ultimate Lair, available on Day 13 if the player completed enough quests to salvage an extra day. While its HP is lower—7,500,000 on Normal—it is less reliant on magic attacks than Aeronite, which means players cannot use Lightning's potential magic immunity to survive. As with Aeronite, Ereshkigal may be fought on the Ark with the same stats it would have if encountered in a Chaos infusion (giving it a maximum potential of 39,375,000 HP on Hard Mode).
On a New Game+ playthrough, the final boss may also be considered a superboss, as his HP rearranges and his attacks become much stronger. Where he has four forms with HP of 600,000, 700,000, 900,000, and 1,050,000 on an initial playthrough, on a New Game+ he has two forms with HP of 4,000,000 and 5,000,000 (or 14,000,000 and 17,500,000 on Hard Mode)—nearly three times more. Additionally, his attack pattern changes (unlike Aeronite and Ereshkigal, who are no more or less aggressive on New Game+/Hard Mode). He is more aggressive, uses more powerful spells, and requires a more specific strategy based on his current form.
The Legacy version had two battles designed to be extremely difficult. The first was the fight against Ifrit (Extreme), the hard mode a required step for the Relic Weapons quest, where Ifrit gained the ability to use Hellfire multiple times during the battle, and his skills were reworked to affect bigger areas of the battlefield (some being unavoidable unless his horns were incapacitated).
The other fight was the hard version of the Seventh Umbral Era final boss, Nael Deus Darnus, an optional battle unlocked by completing the storyline, rewarding victorious players with the White Ravens earrings. The battle began with Nael charging Megaflare (which now deals around 7,000 damage), requiring players to employ extreme damage mitigation tactics to survive the initial minutes of the fight.
In the relaunch, there are many fights that are not part of the storyline. Relatively few can be considered superbosses, as many can be cleared in a matter of minutes with an effective Duty Finder group. For example, players have access to hard mode mode versions of Ifrit, Garuda and Titan, which are required fights for accessing a job's relic weapon.
Patch 2.1 added "extreme" versions of the primal boss fights, providing a third level of difficulty in which to challenge them. The hard mode version of Ultima Weapon is another superboss that debuted in this patch. Similarly, Odin appears in an extremely difficult FATE encounter, and got a designated Trial, Urth's Fount, in patch 2.5.
Sufficiently well equipped players can take on the Binding Coil of Bahamut, a thirteen-part raid whose later floors, or "turns," require nearly perfect play of one's job. In particular, Twintania (Turn 5, the final boss of the original Binding Coil), Nael deus Darnus (Turn 9, the final boss of the Second Coil of Bahamut), and the Final Coil of Bahamut. A harder version of the Second Coil, the Savage Second Coil, was released with patch 2.3, and formerly contained the most difficult raid bosses.
With the addition of the Heavensward expansion, a new raid named Alexander was introduced, containing new normal mode content for casual players, as well as a Savage difficulty level that emulates the difficulty of the Binding Coil series. The Savage forms of the most recent floors of Alexander are currently the strongest superbosses in the game, representing a significant challenge for even the most well-geared players.
List of superbosses:
- See List of Final Fantasy XIV superbosses for the full list of current and retired superbosses.
- A Realm Reborn
Adamantoise is fought in the level 99 hunt Lonely Rumblings in Longwythe, unlocked by the sidequest Let Sleeping Mountains Lie that becomes available upon returning to Lucis with Umbra from Chapter 9 onwards. It is on level 99, has 5,000,000 HP, and it drops either some Adamantoise Meat or Adamantite. The Adamantite Bangle (+10,000 HP*HP is capped at 9,999), one of the best accessories, is a reward for completing the hunt. While the hunt can be repeated to acquire more Meat or Adamantite, the Bangle is only rewarded for the first completion. Defeating the Adamantoise also awards the Tortoise Toppler achievement/trophy.
Ayakashi is a level 110 superboss and is the target of the only other level 99 hunt, Dead General Strikes Down the King. Ayakashi's attacks deal heavy damage or kill the player instantly, so the player should stock up on Phoenix Downs. The first completion of the hunt is one of the only sources of the rare Ribbon accessory.
Bilröst is a superboss found at the end of the toughest dungeon beneath Costlemark Tower, for the level 99 sidequest A Menace Sleeps in Costlemark in Chapter 15. Much of the challenge from the dungeon comes from the inability to use items against the strongest enemies, potentially leaving the party in a weakened state when they finally reach Bilröst. However, Bilröst as well as some of the more challenging enemies in this dungeon, use elemental attacks, and there are recipes that render the characters immune to elemental damage. A Menace Sleeps in Costlemark is the highest level, and typically last completed, portion of the Menace Beneath Lucis sidequest, which awards the Hunter's Medal, the most powerful Elemancy catalyst.
Naglfar is a superboss in the Wondrous Weapon sidequest in Chapter 15. It is level 120, making it and Ayakashi the only enemies above the level cap of 99 at the time of release (patch 1.05 increased the level cap to 120). It drops the Squirming Bone item, which can be given to Randolph to obtain the Zwill Crossblades, the best daggers.
MA-X Angelus-0 is a superboss that can randomly attack from imperial dropships in Chapter 15. It is a powerful magitek armor, and while it has only 202,000 HP, it takes only 10% damage from all sources, giving it the equivalent of 2,020,000 HP. It has a 5% chance of dropping a Magitek Suit V2 (+2000 HP, 100 Strength, and 70 Vitality), a top accessory. It can be fought repeatedly to try and get this rare item. If it doesn't drop the Magitek Suit V2, it will instead drop a Magitek Suit, a slightly worse version of the accessory.
The Dread Behemoth and Tyreant are superbosses that can be fought during daily Timed Quests. The Dread Behemoth is level 140 and can be fought every 10th of a month, whereas the Tyreant is level 130 and can be fought at the 24th of every month. At the 31st of a month both can be fought at the same time, creating possibly the most challenging fight in the game. They are the only two enemies that surpass the player level cap of 120 and have attacks that deal huge amounts of damage to the player. Defeating one of them alone grants 200 QP and defeating both simultaneously grants 500 QP, the highest amount any Timed Quest grants upon completion. Both enemies originally appeared on several occasions as Timed Quests when those were still online based.
The DLC episodes have several optional fights against other player characters. In Episode Gladiolus the player can fight Cor. In Episode Prompto the player can fight Aranea. In Episode Ignis, the player can fight Noctis. These three fights are considered the greatest challenge in the relevant episode, and can be undertaken after completion. Additionally, there are two level 99 enemies in Episode Prompto that can be considered superbosses, the Kaiser Behemoth and MA-X Angelus Casus.
Elidibus is a mysterious character similar to the Lucavi fought in the final level of the optional dungeon, Midlight's Deep, but he is not significantly more difficult than the final boss, Ultima. The challenge comes from winning the battle while learning Zodiark, a "secret" summon spell, and/or recruiting the Byblos, a unique monster.
The Corrupt Judges await as a post-final boss challenge. Though technically classified as superbosses, they exist in a gray area of this term, as this classification is based on them being encountered after defeating the final boss, Li-Grim. Li-Grim, however, remains the most difficult boss.
The Upsilon class of enemy, one being the red Smoldering Incubus, a rather weak superboss, can be fought in the optional Heritor ability quest tackled before the final ability quest. It is only a prelude to the true superboss, Magick Weapon, a possible incarnation of the Omega Weapon (it was built on the same model, like Smoldering Incubus, a possible incarnation of Ultima Weapon). It can be fought after defeating the Neukhia, the final boss.
Clan Cinquleur members also are superbosses, as the second and third time the player encounters them, they are level 99 and are very difficult to defeat (albeit not as difficult as Magick Weapon). Other superbosses are the bosses of Brightmoon Tor sidequest, and the clans of "The Final Mission," which encounter the party at level 99, and ban the summoning of scions (they can still be summoned, but if the player uses one, they lose the judge's protection).
Nox Suzaku appears from the second playthrough, making it impossible to harvest any phantoma until either Nox Suzaku is defeated or goes away after absorbing enough phantoma. The player needs to ram into the Nox Suzaku with their airship to begin the battle in an alternate dimension. Even though defeating all the shades that appear will cause Nox Suzaku to leave, it will not defeat it. The only way to damage Nox Suzaku is to make it appear first by having a party member die, then attacking it in the brief moment it comes to collect the party member's phantoma.
Gilgamesh in his eight-armed form is an easier superboss than Nox Suzaku. He appears in one of four locations in Orience, and is available to fight from the third playthrough after Chapter 4. He behaves much like his earlier counterparts, requiring Breaksights to do sizeable damage, but also has a few more attacks.
Asura appears as the superboss found at B3 of the Iron Maiden Dungeon. She is difficult to deal damage to and has the highest HP at 999. Story-wise she is the reason for the filling of the Iron Maiden with The Dark (and is also the namesake of the dungeon) after being imprisoned and experimented on by Müllenkamp.
Omega appears as the 50th floor boss in the optional DLC dungeon Infinity Spire. He is far more powerful than regular Infinity Spire floor bosses and uses an attack called Wave Cannon that will hit every Adventurer inside Infinity Spire for 1,000 damage, even if they are not fighting him (although any Adventurer not in battle at the time cannot be knocked out by it). Defeating Omega rewards one of the surviving Adventurers with the Omega Symbol, a level 50 necklace that adds +27 to all stats, as well as a regular medal for completing the floor.
A Wyrm appears as the 99th floor boss of the same dungeon. It is by far the most powerful opponent and is similar to Omega except even more powerful. It has an attack called Tidal Wave that will hit every adventurer in the dungeon for 3,000 damage. On defeat, one surviving Adventurer will get the Ragnarok Prime, a sword that gives +52 to all stats, as well as a regular medal for completing the floor.
These two superbosses are the only ones in the series the player does not get to fight directly.
Great Galdes, the final boss from Final Fantasy Crystal Chronicles: Ring of Fates returns as a superboss. The battle is identical to the Ring of Fates encounter, although the difficulty is ramped up significantly.
Inward Chaos is the final storyline and pits the player against all twenty-two playable characters of escalating level, ending with a battle with Chaos at Level 110. Opponents ranging from Level 100 to Level 150 can be fought in the Blackjack Course in the Duel Colosseum, including a Level 130 Chaos. At these levels opponents have much higher stats than the player's character, and due to being at a higher level gain a bonus to their base Bravery.
The superboss is provided by Feral Chaos. At the end of Confessions of the Creator, the player must battle a Level 130 Feral Chaos with over a hundred thousand HP and unique accessories that grant him powerful support effects. A Level 95 Feral Chaos can be fought earlier in the same storyline as a manikin of the true boss, and is itself the most difficult opponent up to that point.
The Haniwa functions as a superboss similar to Warmech from the original Final Fantasy, in that it appears rarely randomly in a certain area, which in this case happens to be the final area. It's a very dangerous enemy, but is arguably not as powerful as the final boss.
There are six optional bosses that could be consider superbosses.
Each boss is located at the 100th floor of each bonus tower:
- Krinjh: Located at the top floor of the Moonsand Ruins.
- Torte: Located at the top floor of the Holy Tree Tower.
- Rolan and Rekoteh: Both located at the top floor of the Mysterious Lighthouse.
- The Adventurer and the Faithful Fox: Both located at the top floor of the Trial Tower.
The Adventurer appears very similar to her incarnation in 4 Heroes of Light as the superboss. She is also accompanied by her companion Fox. The Adventurer is found in the end-game dungeon, Dimension's Hasp, behind a fake wall at the bottom of the dungeon.
In addition, some of the more powerful Nemeses recieved through StreetPass can rival the Adventurer in power, most notably the two Ba'als. By far the most poweful Nemesis was New Year Limited; Takoizumi.
Ba'al appear as superbosses fought at Fort-Lune. While their power can be reduced by using a Ba'al Buster Ship, when fought at their strongest they rival the Adventurer in power. All Ba'al can be fought at the top of their strength as random encounters around the world at the end of Chapter 4.
There are three post-game superbosses all accessible through Gladiators' Hall:
Each superboss can gain levels, up to a maximum level of 6. Adamantoise and Omega Weapon gain 1 level every two times they are defeated, while Gigantuar gains 1 level every three defeats.
Due to the game's nature, several content is updated on a regular basis. Notably, the Chamber of the Fallen and the Chamber of Arms both feature Trials that test the player's strength and strategy through different means. The bosses released in both can be considered superbosses, because they are far more difficult than any content at the time of their respective release, however, many of them are easily manageable due to future content severely power creeping many of them, most notably the older bosses.
Many of the bosses found are unique, although, the Chamber of the Fallen features regular foes from the series such as Gilgamesh, Malboro, Iron Giant or Omega.
Although both Chambers have no relation to the main story, the Dragon King, Bahamut appears in an optional continent on the world map after beating all the main content from season one. He is an extremely difficult foe and could be considered the superboss from season one being more faithful to the tradition of superbosses being unlocked post game.
After defeating Exnine Bahamut in the Postscript and completing every Intervention Quest, three doors leading to unnamed dungeons (Dubbed "EX Dungeons A, B and C" in the official strategy guide) spawn in the Girl's Tearoom. Each is designed to resemble various previous locations and contain stronger versions of normal enemies.
The completion of all three dungeons reveals a fourth, EX Dungeon Z, which serves as an even greater challenge. At the end of the dungeon is a Cogna named XG (a reference to the titular mech in Xenogears), with approximately 100,000 HP and incredibly high Strength and Defense. Defeating XG rewards players with Girl's Diary, Entry 15 and an XG eldbox, allowing XG to be summoned as a Mega Mirage.