Labyrinth of Refrain is already plenty long for players that just play through the basegame's story, with it taking me over 60 hours to see the credits roll. But, what if we told you there are another 20+ hours of content waiting for you if you complete some special requirements to unlock the post-game? Well, it's true, but we can't blame you if you didn't know about the post-games existence or how to unlock it while playing through the story on your own. It's one thing to figure out how to even unlock the post-game, but it's another thing to defeat the gauntlet of 6 "superbosses" hiding the required Black Pages gating your progress. We've got a list of the bosses you'll need to face, and some tips for how to deal with their monstrous power.
The Black Pages, and Their Significance
As previously mentioned, there are 6 bosses holding the 6 Black Pages that you will need to unlock the post-game, and eventually the True Ending. Each of the well's 6 dungeons (Campanella, Astrom, Melm, Phenom, Umbra, and Amadeus) have their own respective boss, holding their own respective page. Once you have found and conquered each of these bosses and claimed their pages for yourself, you'll need to defeat the final boss and create some Clear Data. Upon loading Clear Data which includes all 6 Black Pages, you'll be asked if you wish to continue the story and will return to Velkuvrana's belly - Ornit.
The 6 Bosses, and Where to Find Them
As mentioned, each of the well's 6 dungeons hides a boss - some more hidden than others. We'll start off with Campanella's boss and go down from there, although the game doesn't necessarily expect you to tackle these bosses in the order that these dungeons appear in the story!
A giant, purple fish. He can be found relatively easily - he's hidden past a gauntlet of breakable wall puzzles on B6 of Campanella, around (X22,Y7). He is the easiest of the 6 superbosses to fell - I managed to defeat him during my revisit to Campanella during the story, with a party of mid-80s soldiers.
The first of the superbosses that requires some extra prep to find them. Players might've noticed a sign near the end of Astrom mentioning that "something big" was nearby. Unsurprisingly, once the requirements are met this fight will eventually spawn near here. The trick, is, that you'll need to complete a few sidequests to acquire a book that will allow for him to spawn.
You'll want to complete the sidequest "Skilled Clockworker", which itself is unlocked by completing the sidequest "She Sees Everything!" in Apprentice Notes [Correction: Nearly all Apprentice Notes before post-game need to be completed for Skilled Clockworker to appear]. Since the "Embarrassing Diary" that the latter quest requires only drops in Tanis (the story's last dungeon), you'll be unable to tackle Machina until the very tail end of the story. Upon collecting the diary, the quest we actually want to finish will task you with finding an Old Pocketwatch on the B1 of Campanella. You may have already received one of these earlier in your travels, in which case - good work if you didn't sell it! You just saved yourself a lot of time, as it only spawns at treasure points on this floor. On the flip side, you can break a wall at (X16, Y25) to uncover a chest that when unlocked with the Furia Key you can find in Tanis will contain an Old Pocketwatch for you.
Complete the sidequest and head to the newly spawned Event Point in Astrom to initiate the battle.
By far the superboss that requires both the most prep and the most curiosity to find and defeat. Junon is found in the Holy Mausoleum in Melm - the bottom floor of the dungeon. Yes, the Wing Temple is not the bottom floor. Maybe you noticed a specific hole on this floor in your exploration and discovered the new floor yourself, but if not you'll need to drop down a hole at (X14, Y26) to reach it. But before that, we're going to need a certain Pact in order to even damage her, which can be found in an entirely different dungeon.
You probably noticed this Event Point during your revisit to Campanella, but on the Eastern side of B7 you'll have a fight with a lone Lamb monster if you haven't already and receive Bah-Bah's Pact. You'll need this pact in order to cast Divine Exposure after Junon puts up her barrier - otherwise, none of your attacks will connect. Defeat her (keeping care to defeat her minion that heals her first!) to receive the next Black Page.
It's impossible to miss this one, and chances are you might've run into it on your own during the game. This particularly large Pecoro is standing at (X15, Y3) in "Fallrealm/Gem" in Phenom. It's stronger than Devon, so wait until you're at the endgame before challenging this one.
You'll have talked with her, as well as already have defeated her lower half once by the time you'll get the option to challenge this boss for real. After clearing Umbra you may challenge her by entering her room again at (X15, Y04). You'll require the Vorpal Cane, which you either receive from your first fight with King Alice in Umbra, or through your second encounter with him in Umbra's basement.
Furfur is the hardest of the superbosses to defeat. You can't even damage her until she debuffs herself, allowing your attacks to deal damage. As she gets closer to death she'll target your party members to take a bite out of, restoring her health in the process. She's a test of both your defenses and your DPS, leading up to the post-game so challenge her last.
Zlavec is found at the very bottom of Amadeus, where you originally see the scene of Oracle being devoured. Unsurprisingly, if you return to that same location Zlavec lashes out at you. Defeating him will award you with the last of the Black Pages required to access the post-game, and open the path towards the True Ending.
Ornit, and the Extra Dungeon
Once you have collected all of the Black Pages, defeated Baba Yaga, and continued from your Clear Data you'll find yourself in Coven's largest, most complex, and most difficult dungeon - Unclean Ornit. Each floor itself is based on a dungeon from the main game, with the final floor being entirely new. There's not much help we can give you here - if you've made it this far, you should have an idea of how to format your team, and what your strategies will be. The only thing I can say is that you'll want to take advantage of Soul Transfer, especially for the final boss. Take advantage of stockpiles when you can, and if you find a good spot to grind make use of it if you find it necessary. Good luck.