If you are unsure which Boss you are looking for, have a look at my Walkthrough. There you will find a list of the places, just choose the nearest location to where you are and you should be able to find out which boss you are dealing with.

Disc Three Bosses

• Name :
  1. Dragon Zombie.

  Powers :

  HP=13,000, MP=400.

  Leaves When Dead :

  Cauldron, X Potion, Steal-Cauldron, Morph-Vaccine, Enemy Skills- Shadow Flare, Pandora's Box, EXP 4000, AP 300.

  Location :

  Northern Cave

  Description :

  Ok, technically, I think, Dragon Zombie is not a boss, but you'll find him on your way to the final boss fights with Sephiroth and he's significantly nasty enough to get some attention.

  Best Attack Tactics :

  Like most undead creatures he hates it when you use holy and Heal based spells.

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  Name :

  2. Iron Giant.

  Powers :

  HP=20,000, MP=100.

  Leaves When Dead :

  Phoenix Down, Steal-Elixir, Morph-Escort Guard, EXP 10,000, AP 150.

  Location :

  After the Dragon Zombie fight you'll next run into the Iron Giant.

  Description :

  Again, this guy isn't technically a boss, but he, like Dragon Zombie, is a pain in the neck designed to weaken you a little before you get to Sephiroth.

  Best Attack Tactics :

  He is weak against Ice.

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  Name :

  3. Jenova-Synthesis.

  Powers :

  Torso, HP=60,000, MP=800. Right Arm, HP=10,000, MP=600. Left Arm HP=8000, MP=600.

  Leaves When Dead :

  N/A.

  Location :

  Northern Cave.

  Description :

  Best Attack Tactics :

  The arms go limp after you've killed them, but if you don't kill the torso quickly enough she'll just regenerate them and you'll be up for a three-way battle all over again. The other catch to this fight is the countdown she does. When she gets sufficiently weak she'll start a countdown to a casting of ultima magic, if you don't kill her on the turn after she starts the countdown you're going to get hit. For the most part, like the Dragon Zombie and the Iron Giant before her, this is a diversion to make you use some MP and lose some HP before Sephiroth.

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  Name :

  4. Bizarro-Sephiroth.

  Powers :

  Head, HP=40,000, MP=1000. Torso, HP=2000, MP=400. Core, HP=10,000, MP=400. Left-Magic, HP=4000, MP=400, Right-Magic, HP=4000, MP=400.

  Leaves When Dead :

  N/A

  Location :

  Northern Cave

  Description :

  As you can see, there are five parts to this guy so the thing to do is to make sure you use a lot of summons and use spells that are linked to an All materia so you can hit all of him at once.

  Best Attack Tactics :

  Here's how this fight works--you have to destroy the Left and Right-Magics of Sephiroth first in order to give you a chance to weaken the Core, once you kill off the Core then you can attack the Torso--once the Torso goes you win (so obviously there is no reason to worry about the head as it doesn't play any role in this chain). This sounds pretty easy until you find out that the Core can heal the Torso and it can regenerate the Right and Left-Magics, making it a little tough to get a chance to start weakening the Core which will let you get to take out the Torso.
  The thing to do, especially if you have multiple parties, is keep attacking opposite sides of this guy. Use the team on the right to focus on the Right-Magic and the team on the left to focus on the Left-Magic. It is a very good idea to have a bunch of Mime's and a few KORs at this point. Sephiroth hits with a lot of magic so the Big Guard Enemy Skill is a must (because it will cast Barrier, MBarrier, and Haste on everyone) for each party. It is also a good idea to have each party's Enemy Skill list include White Wind for a quick healing when things start looking grim.
  Sephiroth has a magic attack called Fallen Angel, this reduces everyone's HP to 1 so it is a very good idea to keep Cure 3 handy for each group--if you've got the ability to keep all of this straight without going insane, it is also a good idea to keep everyone covered by Regen, that way as soon as your HP falls to one it will begin building again while you're casting Cure 3. Final Attack-Phoenix (or Final Attack-Revive, is a must for as many characters as you can link it to!). If you can start off with KOR and have everyone Mime it this isn't too tough of a fight. Keep in mind that if you have multiple parties you can only Mime spells cast from that party--so if you have a party on the left and the right and the left side attacks first with KOR then no one on the right will be able to Mime that KOR because it didn't happen over there.

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  Name :

  5. Safer-Sephiroth.

  Powers :

  HP=73,000 MP=2000.

  Leaves When Dead :

  N/A.

  Location :

  Northern Cave.

  Description :

  This is the final battle, and it's not really a nasty one. He's got some pretty good attacks--Pale Horse does some minor physical damage and hits the character with every status effect in the book, Ribbon will protect you from most of these but you better have the Esuna spell handy or a few Remedies in your item pack to get the rest. He's got a Shadow Flare spell that hits one character for around 7000 HP damage. He's got a weaker spell called Deen, it does 1000-2000 HP damage, but that can add up pretty fast. He's also got a Super Nova summon, this summon takes forever to cast, and it hits for somewhere between 3000 and 5000 HP to everyone. He also has a habit of setting up a Barrier on himself so be sure you've got Debarrier equipped.

  Best Attack Tactics :

  The things you need to do are cast the Big Guard Enemy Skill (as this will decrease the damage Sephiroth does) and keep things like White Wind and Angel Whisper Enemy Skills handy as well as Cure 3 and Regen so that you can stay alive. The Shield-All combo is a pretty smart move too! Offensively you need to hit with anything that allows you to attack more than once--have 2x-Cut equipped to as many characters as you can--cast spells like Comet2, use limit breaks and KOR--anything to hit this guy often and hard.
  This is the last battle in the game--now you are done! Just sit back and enjoy the 20 minute ending :-).