Colossus

 (Colossus) — is an enemy that only appears during the Blood Moon event.

Behavior
Colossus uses two attacks - if the player character is close, he will strike the ground with his stone club, creating a small shockwave. If the player character is far away or is in the air, Colossus will shoot a damaging laserbeam from his eye.

In addition, the Colossus doesn't damage on contact, so it's much easier to kill him in close combat, skillfully counting the time between his attacks (you need to remember that damage from shockwaves is much higher when the player is near to Colossus).

Trivia

 * If you kill Colossus during his laser attack, he will drop 1 Lens.
 * Colossus' appearance is resembling to analogous boss from Risk of Rain.