Necron is the final boss of Final Fantasy IX, fought at the Hill of Despair. After the party has been weakened by Trance Kuja's Ultima spell, the four party members selected to fight Necron will be recharged by the other comrades. The player does not have to use Zidane for the final battle.
Necron is not as powerful as Ozma, but still should not be underestimated. Necron has a plethora of magic spells, including Firaga, Blizzaga, and Thundaga, which hit for around 1,500+ damage on all the characters. Necron can also cast Holy and Flare, which hit one character for around 3,000 damage. Necron can perform three actions per turn, putting the party at a disadvantage, especially if he casts Grand Cross, since Neutron Ring follows almost immediately after.
Necron will buff himself with Protect and Shell, and will cast Curaga to heal around 2,500 HP should he feel threatened. Like most final bosses, Necron has an attack to bring one character to 1 HP: Blue Shockwave. Necron's Neutron Ring deals around 4,000+ damage to all characters. His most devastating attack, Grand Cross, functions similarly to Malboro's Bad Breath, only it inflicts most of the status ailments in the game, including Heat/Freeze.
Before fighting Necron, the player will have the opportunity to check the party's equipment. It is highly recommended that every character has the immunity abilities Clear Headed, Body Temp, Antibody, Locomotion and Jelly to block some of Grand Cross's negative effects. One can also equip some other supportive abilities, like HP+, Auto-Regen, and Auto-Haste.
It is advised to equip the Bird Killer and MP Attack abilities to increase the damage inflicted to Necron. The party can mimic Necron by casting Protect and Shell to guard against his Neutron Ring and elemental magic. Freya's Dragon's Crest, Vivi's Flare, Zidane's Thievery and/or Dyne, and Steiner's Shock are good damage dealers. Amarant's Aura can also be used to cast Regen and Auto-Life.
Quina's powered up Frog Drop is an easy way to deal damage and Quina can also cast Auto-Life and remove all of the party's status effects with Angel's Snack, as well as buff the party with Mighty Guard. If the party has any Elixirs left in the inventory, this is the time to use them. Necron himself also carries four Elixirs so Zidane can steal them if the party runs out. Freya can avoid the Neutron Ring and Grand Cross attacks with the Jump command, especially if she has also achieved Trance.