Major Numerus is a superboss in Final Fantasy X-2: International + Last Mission and the Final Fantasy X-2 HD Remaster. It is a Hydra-like fiend that consists of four parts, each with unique attacks and statistics—Unum, Duo, Tria, and Quattour—and will start out the fight with Spellspring.
Major Numerus has incredible stats, and has access to over 30 abilities, making it one of the most difficult superbosses in Final Fantasy. Major Numerus acts quickly, and will use its most devastating attacks at a whim, and Protect and Shell on all of its heads. Therefore, the player party should be equipped with Haste since the start of the battle. The player must be extremely fast and fluid to stand against Major Numerus.
The battle depends on the speed and playtime the player has done. The more times the game has been played, the slower it gets, so the freshest mechanics from the game's playtime are required.
With invincibility Edit
Before fighting Major Numerus, the party's level should be 99, with all abilities of the Mascot dressphere mastered. Rikku must have learned Dispel from the White Mage dressphere, and Paine must have learned Nonpareil from the Samurai dressphere. The key to the battle is Miracle Drink, making the party invincible to damage. It must be cast at the very start of the battle, because the party—even well-prepared—will likely be killed within a minute or two.
The player must have at least one Dark Matter and mix it with a Potion to mix Miracle Drink. Invincible, or anything that grants Break Damage Limit, like the Last Resort Garment Grid, is needed. One girl must also equip the Highroad Winds Garment Grid for First Strike, and move the Dark Matter item to the top of the inventory.
At the beginning of battle, the player should quickly mix Miracle Drink. This takes a lot of luck to not have any of the girls killed while waiting for it to happen. If a girl is KO'd, the player can still win, but it will be very difficult. Afterwards, if the player doesn't have Invincible on and they are using a Garment Grid that has Break Damage Limit, the player should quickly use that gate. This is also worth doing for No MP Cost (the Last Resort Garment Grid has that as well) or use Three Stars to get the same effect.
Paine should use Nonpareil three or four times to increase her attack. Afterward she will focus on using Cactling Gun, with Yuna using Moogle Beam. Rikku has two roles since she will have to deal with Numerus casting Protect and Shell on his heads. When both have been cast, the player should dispel all but one of the heads. Leaving one head with Protect and Shell on will mean Major Numerus won't cast it again. Paine and Yuna should concentrate on one head at a time. Rikku's second role is to chain her physical attack with Cactling Gun and Moogle Beam.
With this strategy, Major Numerus can be beaten in around 18 minutes.
Without invincibility Edit
A strategy that doesn't involve invincibility is to have all three girls equipped with two Iron Dukes on either the Higher Power or The End Garment Grid. The girls should start off the battle in the Thief dressphere (First Strike must be learned) and then activate the gates necessary for Break Damage Limit as soon as the fight begins; they should end up on a Mascot node. Yuna must immediately ready Moogle Cureja, Rikku must use a Stamina Tonic to double the party's HP, and Paine should use a Megalixir. All three girls should prepare to heal with Moogle Cureja or Megalixirs to survive the upcoming attacks.
With around 40,000 HP, the party should survive both Unum's Ladis Command and Quattour's Mortis Command. Yuna must continuously use Moogle Cureja while Rikku heals with Megalixirs and Paine readies for battle using Nonpareil and maybe Hayate. Paine should be the only one focusing on Numerus, as constant healing from Yuna and Rikku is essential. After using Nonpareil five times, Paine should use a Dispel Tonic on Unum to remove his Protect, then start using Cactling Gun. If Unum recasts Protect, Paine must dispel it again.
Unum has 555,555 HP, so 7–8 Cactling Guns should take him out. At this point, the party no longer has to fear the devastating Ladis Command, and no longer has to throw Megalixirs constantly, as Moogle Cureja should suffice. Paine's next target should be Quattour, because he is the one using Mortis Command. She should dispel his Protect. With sufficient healing from Yuna, Quattour should fall in a reasonably short time.
At this point, Major Numerus's most devastating attacks have been eliminated. The player can now be more offensive, casting Moogle Regenja to put all three girls in Haste and have Yuna and Rikku be physical attackers, healing from time to time, while Paine continues to use Cactling Gun.
This strategy will require around 30 Megalixirs as well as significantly more time than the other strategy. Having two accessories that give +100% HP is mandatory. Two Iron Dukes per girl is ideal, but to make up for missing a second Iron Duke, it must be replaced by Key to Success or, failing that, Crystal Bangles (the latter, however, will be more difficult).
Captured Fiends Edit
The captured fiends and/or humanoids that have incredible stats, like Almighty Shinra, are recommended, but they must also be equipped with the Mascot dressphere (as it makes them immune to status ailments), two Iron Duke accessories (which maxes out almost all stats), and the Hero's stash ability (which grants the Hero Drink effect) to stand against the Major Numerus' attacks.
Numerus is Latin for "number". Unum, duo, tria and quattour mean "one, two, three, four" in Latin respectively.