The Blue Screamer is a mob that spawns in the Foglands at any time of day, in the fog. As the name suggests, it is a dull blue color with an unnaturally wide mouth open in a constant scream. Its eyes also appear to have crying marks, similar to that of a ghast.
The blue screamer is hostile and attacks by screaming at the player, firing a loud sonic blast projectile out of its mouth. These blasts deal 7 sound damage. The mob will turn its head so that a new mouth is facing the player after each attack. The Blue Screamer can also deal 7 regular damage in a melee attack if the player gets too close.
Blue screamers will grief player-placed torches and can also break player-placed blocks to get to the player. They can be equipped with weapons and armor via console commands, but will never spawn with them naturally. Blue Screamers can use projectile weapons (such as bows and crossbows) in tandem with their screams if they are so equipped.
These mobs can also swim much like the player, and are agile underwater, but nonetheless have a limited supply of oxygen. Though their sound attacks do 1.5x damage underwater, every scream will deplete their oxygen supply rapidly.