Flairon

The Flairon is dropped by Duke Fishron at a 1/5 chance. When thrown, it blows bubbles which will chase after nearby enemies. It deals less damage than the Scourge of the Corruptor, but creates far more homing projectiles.

Though it resembles a standard Flail, it is actually more similar to the Chain Knife or Golem Fist in operation - it is unaffected by gravity, and does not remain deployed while the attack button is held down.

Trivia
Flairon seems to be a portmanteau of the words Flail and Fishron.