Note: For an INSANELY easy time with some of the "Bosses" here, Equip the Blood Sword(s) on someone and watch them drop like flies.
Well, welcome to the final area in the game. If you need to heal up or exit this place or do something, Warp out of here now and do so, then make your way back here. Whenever you're ready, let's move on. First, head south and follow the path here, ignoring those "doors" all around, as they aren't anything you can enter and just continue on until you come to some stairs. Head up them and on the next floor, head northwest to find a Treasure Chest, which holds an Ether, then just follow the path and step onto the teleporter you find to head to the next floor. On this floor, head south and grab the Treasure Chest you see to get an Eye Drops, then head northeast as far as you can go, then head south and step onto the teleporter you find.
On the next floor, get ready to get some REALLY good Equipment here. First, enter the door farthest to the west and in this area, follow the path and open the Treasure Chest you come across to obtain a Genji Gloves, which is guarded by Zombie Borghen! Damn, this guy's back? Well, he's stronger than before, but I don't count him as a Boss, since he's just in a Treasure Chest. Besides that, this game's ideas for Bosses are just Enemies you'll meet later on, so, really, it's pointless. Anyway, just kill him and afterwards, give the Genji Gloves to whoever you wish, then head east and once you reach a dead end with a pillar nearby, try pushing up against the wall to the east and you'll find a hidden room with a Treasure Chest, which holds a Masamune, THE strongest weapon in the game, PERIOD.
Give this to Firion or whoever you wish and then give someone the Excalibur if it's better than what they have currently. After this, head back to the start of this area where all the doors here and now, enter the door second to the west and in this area, just follow the path and grab the Treasure Chest you come to get a Genji Helmet, which is guarded by Tiamat. Again, not worth a strategy, so just kill him as fast as you can, which should NOT be a problem at this point. Afterwards, give the Genji Helmet to someone else now, as you'll notice the Genji Equipment is AWESOME and you'll want to share the wealth with your other party members. Next up, head back out of here and enter the door farthest to the east now and in this area, follow the path and grab the Treasure Chest here to get a Genji Armour, but it's guarded by Beelzebub.
Again, not that hard, so just destroy this thing and move on. Also, give the Genji Armour to someone else like before so they get a ton of Defence Points. Next, head out of this area and back in the main place where you started, enter the door second to the east and in this area, follow the path and grab the Treasure Chest you come across to get a Ribbon Helmet, but it's guarded by Astaroth, the second hardest Monster in the game. Basically, just assault her, as she's not THAT tough, even for that strong of a Monster, which is pretty sad, really… anyway, after this, don't bother with the Ribbon Helmet at this point in the game, as the chances of Status Ailments even hitting your guys is so low it's not even funny.
So, next, continue on the path and step on the teleporter you come across and back on the previous floor now, just follow the path and step on the teleporter you come across. On the next floor, follow the path and grab the Treasure Chest you see to get a Sage's Wisdom, then continue on the path and step on the next teleporter you come across. On the next floor, head north and grab the Treasure Chest you come across to obtain an Acid Bottle, then head southeast to find the last Treasure Chest in the game, which holds a Hellfire. Good job, I hope that last Item made your percent reach 100%. Either way, head north now and before you step on the teleporter here, make SURE you are ready to continue. Make a Memo File Save if you must, but when you're ready, step on the teleporter here.
On the next floor, just head southwest and step on the teleporter you find and then you'll reach the final floor. To the north is the final Boss in the game. Use anything and everything to completely heal yourself in every which way, Equip anything you need and DEFINITELY put a Phoenix Down and Elixir in everyone's Item Slots just incase. Also, before you start this last Battle, if you wish to beat this easily and "cheaply", Equip the Blood Swords if you have them. Seriously, you'll win in like 2 hits. Although, if you want to win the fair and square way, that's not a problem. When you're ready, head north and talk to Emperor to finish this once and for all…