Uses own MP to raise Attack Pwr.
Description
MP Attack is a support ability in Final Fantasy IX for physical attackers, allowing them to increase the power of their Attack at the cost of 1/8th of their maximum MP per hit. It costs 5 Magic Stones to equip. There is no visual cue to MP Attacking taking effect other than the attacker consuming MP.
MP Attack calls back to Final Fantasy V and Final Fantasy VI where certain weapons consumed the wielder's MP on hit to deal more damage.
Obtained[]
MP Attack is learned from Red Hat, Cross Helm, Battle Boots, and Power Belt for variable amounts of AP; Freya learns it the fastest at 20 AP, where Amarant requires the most at 60 AP.
The first source for everyone is from the Power Belt, obtained for free during Princess Garnet and Captain Steiner's visit to Treno with Marcus. The player can view an Active Time Event called "Treno Tradition", in which Garnet is mugged by a pickpocket called Four-armed Man. An exclamation mark will appear, and if the player presses 
when it appears, Garnet loses 500 gil. The sum is 1000 gil if the player misses. After witnessing the event, Steiner can go to the same location (right outside the Synthesis Shop) where he meets the Four-armed Man who hands over a Power Belt. Power Belt is also found in synthesis shops later.
Cross Helm teaches MP Attack to Steiner and Freya, first obtained by unequipping it from Beatrix during the Battle of Alexandria. Red Hat teaches the ability to Zidane and Amarant, first bought from Esto Gaza after the events in Desert Palace. Battle Boots can be worn by everyone, first synthesized in Daguerreo or obtained as a reward for catching 45 frogs.
Mechanics[]
With MP Attack, using Attack deals 150% normal damage. It stacks with Killer abilities and Elem-Atk gear, and the attack can still critical. If the attacker also has Healer (only possible with Amarant), the amount healed with Attack is increased. MP Attack does not boost damage if the wielder has 0 MP, but works as long as the attacker has at least 1 MP. MP Attack affects any use of Attack command: via Attack, Charge!, or Counter. It does not affect damage from any other move besides the basic Attack command.
Use[]
Using MP Attack will quickly drain the attacker's MP, as it takes only 8 Attacks to use it all up from full MP. MP Attack is thus saved for boss battles, or when the player has means of replenishing mana, such as with Tents while exploring the world map. If the player has a stock of Ethers, they work best when used with Chemist. Zidane may be able to easily procure more MP-restoring items via Steal. Amarant can replenish one ally's MP with Chakra, but using up some of his turns for MP-restoration takes time away from attacking, and so may not be any more effective than using Attack without MP Attack. He could use Counter for free Attacks and then use his turns for Chakra.
Freya can replenish MP with Lancer or White Draw, but they also cost MP to use in themselves. White Draw and Zidane's Sacrifice restore MP to all of the party.
Killer abilities raise Attack as much as MP Attack, and do not cost anything, but it depends on the target if they will work. Both can be used at the same time to raise Attack to 225% damage.
Zidane's Skills use little MP, and so he mainly needs MP in Trance for Dyne. He could be an ideal candidate for equipping MP Attack.
By the endgame, Zidane, Freya, and Steiner can learn powerful abilities that they can use instead of their Attack for most of the time: Thievery, Dragon's Crest, and Shock; the first two also take less MP than MP Attack would. Thievery is tedious to power up, however, so Zidane may fare better with his normal Attacks. Freya could also use Jump with High Jump equipped. Attack remains Amarant's best damage-dealer when boosted with Killer abilities, MP Attack, and/or Kaiser Knuckles with Bracer, though his No Mercy is also strong. The boon of using Attack command over the characters' special moves is that they can also use Add Status (does not work with Zidane's thief swords).