Slammer

Slammers are big blue birds with five eyes and pink darts embedded in their back. They are found in the Corrupted Prison, Cavern and Astrolab.

Behavior
When a Slammer detects the player, it will jump at the player to get within range. It can jump between platforms to chase the player. If the player is on the same platform as them, it will do a faster leap forward.

Slammers are immune to stun.

Slammer Elites, on top of any Elite special abilities, are faster than normal.

Strategy
Slammers are one of the most dangerous enemies in the game. They have exceptional DPS, health, attack rate, range & response times. Their only real weakness is that they are vulnerable while they are jumping between platforms. You can exploit this to get one free hit on them right when they land. Rooting them while their back is turned against you is the most effective way to kill a Slammer, which it can't do anything about. Burst damage and freeze skills are very useful to have in case you can't kill a Slammer fast enough.

Alternatively if there are climbable chains nearby you can take advantage of them and use deployed skills without worrying about the Slammer's attack, since it cannot hit you from there.

If you do let a Slammer start attacking, stay on the air for as much as possible, especially while they are facing you. Get behind them as fast as possible and run to a different platform.

Slammers should be fought 1v1 whenever possible. If there are too many enemies around it, use the Homunculus Rune to draw aggro. Do not dive attack into it because they will not be stunned by it.

Trivia

 * Slammers were added with the v1.2 update, aka Rise of the Giant DLC in March 2019.
 * Slammers used to be giant bats according to a Rise of the Giant preview, possibly explaining their stun immunity via echolocation.
 * However, notes in Astrolab contradict this, stating that they are simply mutated crows.
 * Slammers lack feathers on their body and wings, probably explaining why they cannot fly. The tranquilizer darts and collar with a broken chain hint they may have been beasts of burden before the Malaise outbreak.