Nightmare

Nightmare is a Sea Creature that can be spawned from fishing during a Spooky Festival. It can be fished up after reaching (14).

It's special ability can toss you up in the air, dealing damage and causing fall damage to take place afterwards.

Spawning
If the player has (14), a Nightmare can be fished up from any Water source with a Water Fishing Rod during a Spooky Festival. The base chance for a caught Sea Creature to be a Nightmare is.

Trivia

 * It is the only current use of the Zombie Horse entity.