Narcissus

Narcissus is an optional boss added in Revelations Chapter One and can be found in the Mirror Room in the Glacier. He is one of Revelation's bosses that is not based on a base-game boss. Narcissus is a special boss that works into Revelations' story. The whole boss fight is symbolic, and also quite literal, of fighting one's reflection. Narcissus will always drop Mirror Shard when defeated, which will work its way into subsequently released Revelations' chapters (like how Key Piece 1 and Key Piece 2 work). Revelations adds in Health Scaling for their added bosses. Narcissus' health will be set at the beginning of the fight dependent on whichever number is higher between 200 or the player's damage times 20.

Behavior
Phase 1 Phase 2 (starts at > 75% health, or after 25 seconds)
 * The player fights Isaac, who stays at a distance from the player, occasionally firing a single tear.
 * Isaac sinks into the mirror, and smashes it, emerging as Narcissus.
 * Regularly fires a singular tear towards the player
 * Occasionally hits a mirror bomb at the player, which sends tears out in 6 directions
 * Narcissus has a few smash attacks he performs
 * Smashes the ground, sending a wave of mirror shards directly towards the player.
 * Smashes the ground, sending 5 split mirror shards out in a star-like pattern.
 * Smashes the ground, sending mirror shards out in all directions for a short distance
 * Narcissus can perform a variety of attacks that resemble base-game active items.
 * Anarchistscookbook.pnghist Cookbook - Summons 4-8 troll bombs.
 * The troll bombs can damage Narcissus, but the damage done is very minor.
 * Bluecandle.png Candle - Fires a large fire that slowly burns out.
 * Bobsrottenhead.png's Rotten Head - Fires a bomb towards the player
 * This attack poisons Narcissus if it hits him
 * This attack can also kill spiders and flies spawned by Narcissus
 * Bookofshadows.png of Shadows - Makes Narcissus invincible for a short time.
 * Boxofspiders.png of Spiders - Spawns 2-3 spiders.
 * Butterbean.pngr Bean - Knocks the player back.
 * Doctorsremote.pngr's Remote - Puts a target on the ground that follows the player. After a small amount of time, an Epic Fetus rocket will land towards the target.
 * This attack cannot hurt Narcissus, but it can hurt spiders and flies spawned by him.
 * Glasscannon.png Cannon - Sends out a large mirror tear at the player which deals a full heart of damage.
 * Only usable at low health. Sets Narcissus's health to 1.
 * Guppyshead.png's Head - Spawns 3-4 flies.
 * Kamikaze.pngaze! - Explodes Narcissus, dealing damage to himself, the player, and spiders and flies spawned by him.
 * Monstrostooth.pngro's Tooth - Monstro falls from the ceiling, coughing a large amount of tears at the player. After the attack, Monstro jumps up and leaves the fight.
 * Monstro is invincible and cannot be damaged or defeated.
 * Monstro does not do contact damage to the player.
 * Shoopdawhoop.png Da Whoop! - Fires a brimstone laser either left or right, dependent on the player's location.
 * Tammyshead.png's Head - Shoots 10 tears around Narcissus.
 * Telepathyfordummies.pngathy for Dummies - Gives Narcissus' tears homing for a long time.
 * Applies to Tammy's Head, his bomb attack, ect.
 * Doctorsremote.pngort - Teleports Narcissus
 * Yumheart.png Heart - Heals Narcissus
 * Only usable twice per fight

Trivia

 * Narcissus is made out of mirrors and is a representation of a reflection of Isaac.
 * Narcissus makes use of Active Items extensively, morphed into versions that are harmful to Isaac.
 * According to the code, Narcissus' name was originally "Narciccus."
 * Early in development, Narcissus was called "Corinthian", a reference to 1st Corinthians 13:12 in the Bible, which talks about mirrors
 * For now we see only a reflection as in a mirror; then we shall see face to face. Now I know in part; then I shall know fully, even as I am fully known. (1st Corinthians 13:12)
 * According to the game files, the Narcissus boss fight was either supposed to be entirely of Isaac using the same attacks, or Phase 1 being able to use the same attacks (see Gallery).
 * In Greek Mythology, Narcissus was a hunter from Thespiae, son of river god Cephissus, who was well known for his beauty. Narcissus was so proud of his beauty, that he brushed off those who loved him, for he thought they weren't worthy of him. Nemesis, who enacted punishments to those who showed arrogance to the gods, noticed this, and lured Narcissus to a pool of water. Seeing his reflection, Narcissus fell in love with himself, not realizing that it was a mere image. Unable to look away from his beauty, Narcissus lost the will to live and stared at his reflection until he died. (Info taken from this page).
 * This story is also the origin of the word narcissism, which is described as "excessive or erotic interest in oneself and one's physical appearance."
 * The difficulty of the boss and his later counterpart is likely based on how the player must shatter a mirror door to access him. Shattering mirrors is believed to be a bad omen.