Flood

The Flood is an Unversed that is found in Kingdom Hearts Birth by Sleep and Kingdom Hearts III. It is the most common form of Unversed.

Kingdom Hearts Birth by Sleep
Floods tend to be the first Unversed to appear whenever, Terra, Aqua and Ventus visit a world.

In Enchanted Dominion, a group of Floods attack Terra as soon as he arrives. He slays all but one, which he chases to a bridge leading to King Stephan's castle.

In Castle of Dreams, Floods are attracted Cinderella's despair after her ballgown was ruined by her wicked step-family. Terra later spots some on the balcony above the ballroom.

In Dwarf Woodlands, Floods appear and scare Snow White into the forest, leaving Terra to dispatch them.

In Radiant Garden, a swarm attack Terra upon his arrival, confirming that Vanitas is there. Some later chase a young Kairi, prompting Mickey and Aqua to team up to get rid of them.

Aqua finds them upon her arrival in Deep Space.

At the Keyblade Graveyard, Floods are among the many Unversed summoned by Vanitas. He uses three of them to bind Ventus, so he force him to merge back together, creating Ventus-Vanitas.

Kingdom Hearts III
Floods appear in the lobby of Monsters, Inc. along with Spiked Turtletoads, much to Sora, Donald, and Goofy's confusion, as they are not familiar with the Unversed. Goofy later remembers that Yen Sid had warned him about them, and that it had been a very long time since they appeared. Floods are seen entering doors to scare children and collect the energy from their terror.

Design
The Flood is a sleek, humanoid creature with blue skin. Its arms and legs end in points and have no distinct digits. It has a triangular head with two long, jagged, lightning bolt-shaped antennae reminiscent of the Unversed symbol. Its red eyes are set in an angry expression, and it moves in a jerking, twitchy motion. While most Floods are roughly the size of a Shadow Heartless, some in the Keyblade Graveyard are shown to be quite large. It is the only generic Unversed that does not have an Unversed emblem on its body.

Like all Unversed, the Flood is created from a negative emotion.

In Kingdom Hearts Birth by Sleep Final Mix, the Flood receives a palette swap which gives it a purple body and fuchsia antennae.

Interestingly, the Flood's behavior mimics that of a Shadow, the basic form of Heartless, and a Dusk, the basic form of Nobodies. Like Shadows, the Flood is able to sink flat into the ground and become temporarily invincible. Like Dusks, a Flood's body stretches and contorts when it spawns.

A "flood" is an overflow of an expanse of water that submerges land. This could refer to the danger Floods pose in great numbers and their blue coloration, as well as "overflowing emotion".

Kingdom Hearts Birth by Sleep
The Flood has a similar fighting style to a Shadow Heartless. It sinks into the ground to avoid damage and attacks enemies with its claws. The player can easily defend against a Flood's attack by watching for it to wave its arms just beforehand.

Although very weak, Floods can be quite a menace when they appear in large groups. While they often appear alongside larger Unversed, it only takes a few hits from the Keyblade to destroy them. It is also possible to use magic in order to defeat this enemy. If a Flood sinks into the ground, simply wait for it to surface before attacking.

Kingdom Hearts III
Floods act much the same as in Kingdom Hearts Birth by Sleep, and pose little threat individually. Like their Shadow counterparts, Floods can be forced to emerge while sunk into the ground by hitting them with Water attacks or magic. They are also weak to attacks. Watch for when the Flood prowls around or temporarily retreats, as this signals when it will attack.

Floods encountered in the Keyblade Graveyard are unable to sink into the ground.