Dark One

Dark One is a boss that can appear:
 * In all environments of Chapter 2.
 * Only in.

Behavior

 * Sends out a ring of 12 projectiles.
 * If Isaac is below him, fires a laser downwards.
 * Charges twice across the screen, veering slowly towards Isaac while charging. When going off-screen, he reappears from the opposite end of the screen. Dark One will do this attack more often if Isaac moves to one of his sides.
 * Dims the room, causing the Curse of Darkness effect for a period of time.

Trivia

 * The Adversary is the posthumous version of him.
 * One of Dark One's horns is cut off during his death animation, signifying his transformation into The Adversary.
 * Dark One is one of the three bosses that can dim the room (a temporary Curse of Darkness effect). The other bosses are The Adversary and The Lamb.