Pin

Pin is a boss that can appear in.

Behavior
Pin burrows into the ground before performing the following attacks:
 * Jumps out of the ground towards Isaac and burrowing back into the ground at the end of the jump.
 * Occasionally fires 4 projectiles diagonally from the last section of its body when exiting the ground and/or when burrowing back into the ground.
 * Fires 4 projectiles diagonally depending on the length of its jump: does not fire projectiles on short jumps, fires projectiles shortly upon exiting the jump on regular/medium jumps, and fires projectiles both shortly upon exiting and after a few moments airborne on long jumps.
 * Partially emerges out of the ground to fire a red shot at Isaac before returning underground.
 * After performing this attack, Pin will always jump out of the same spot it entered.

Champion Versions

 * Black: Slightly larger and fires a radial burst of 6 spiraling projectiles instead of an explosive projectile and fires 6 projectiles instead of 4 when moving around.

Trivia

 * Pin was added in the Wrath of the Lamb DLC for the original The Binding of Isaac.
 * The Frail is its posthumous version.
 * Prior to Repentance, Pin's Champion version could never appear in-game despite existing in the original Binding of Isaac.
 * Pin is based off the pinworm, an internal parasite.
 * Pin is likely a reference to Lanmola, a boss from The Legend of Zelda: A Link to the Past; as nearly all attacks are the same.
 * It is the boss version of the Needles.
 * Pin is the only boss in Repentance that got a new champion variant.