Catastrochorus

Catastrochorus is an Emblem Heartless boss in Kingdom Hearts III. It is fought near the beginning of San Fransokyo. It is also fought in Battlegate 13 in the Keyblade Graveyard.

Kingdom Hearts III
While Sora, Donald, and Goofy help the newly upgraded Big Hero 6 take out Heartless attacking San Fansokyo, a Catastrochorus jumps into the middle of the street. As the lesser Heartless are still attacking the city, Sora, Donald, Goofy and Baymax destroy the Catastrochorus, while Big Hero 6 takes care of the other Heartless.

Design
The Catastrochorus is a large Heartless resembling a Tyrannosaurus Rex. It is largely colored brown with a grey and black exterior across its head and back, with yellow zig-zagged stripes separating the two. It has a large dino-like head with a sharp pointed horn, a jagged mouth with a lava covered interior, curved yellow eyes on each side of its head, and two lava filled outlets as its 'ears'. Other such outlets are extrude out from across its back, with the largest in the middle of its back resembling a volcano. It has two proportionally small arms and two giant feet, each containing grey blocky claws. It has a blue jar-like tail, upon which is its Heartless emblem.

Strategy
By far the easiest method to defeat the Catastrochorus is through the use of the Sea Spectacle Link summon, which will deal massive damage to the Heartless due to both its weakness to Water damage and its large size causing nearly all the projectiles from the Link to hit the target. Just one effective usage of the Link will be enough to reduce the Heartless's HP to 1 before it can begin its second phase in San Fransokyo, though in it cannot be defeated until the second phase has begun.

However, if Sea Spectacle is not available due to The Caribbean not being visited yet or the usage of the No Links PRO Code, then it is best to play defensively and wait for the Catastrochorus to begin one of its attacks before counterattacking. When casting magic, attempt to use Water magic on its Volcano for extra damage. Be careful when using physical combos against the Volcano however, as the Catastrochorus has a couple attacks to use to defend it. When it gains its armor, consider using a Shotlock to safely deplete its armor from a distance.

During the boss battle in San Fransokyo, the Catastrochorus will jump to one of the buildings and switch to its tail and lightning attacks. Heartless will intercept Sora on the way to the Catastrochorus, so be prepared to dodge projectiles while climbing the buildings, and watch for stray Heartless while attacking the Catastrochorus. Utilize Air Slide to dodge its lightning attacks while getting hits in, as this portion of the fight is most effectively fought in the air.