Adamantortoise is an enemy in Final Fantasy X-2.
Adamantortoise enjoys massive amounts of HP, Defense and Magic Defense, as well as immunity to debuffs and the ability to augment its offense and defense. Its ordinary attacks do negligible damage, but it occasionally uses the powerful Adamant Breath for fire-based damage and Tremor for heavy non-elemental physical damage.
The Samurai's Sparkler and Fireworks ignore defense and Fingersnap can cancel out defensive and offensive augmentations. The Blue Bullet skill Annihilator, acquired very late in the game, can do 9999 damage (or more, if the character casting it has break damage limit) at level 60. It ignores magic defense.
Spare Change is effective albeit expensive. Mortar, Storm Cannon and Flare are other last-resort options with even smaller damage-to-cost ratios. Mortar ignores defense but costs double the cost of the Annihilator and is harder to learn.
Fiend Tale Edit
In the Fiend Tale endings, a notable Adamantortoise is an ancient fiend that has been resting with Shinra probing its mind to learn more about it and Spira's geological history. Returning the fiend to the sea from which it emerged eons ago reveals Adamantortoise was core of Shinra's theory that fiends predate known life on Spira.
Adamantoise is a portmanteau of "adamantite" and "tortoise".
Adamantite and similar words including Adamant and Adamantine are used to refer to any especially hard substance, whether composed of diamond, some other gemstone, or some type of metal.