The Siren

The Siren is a boss added in The Binding of Isaac: Repentance that can appear in.

Behavior

 * If Isaac has any Familiars, The Siren sings, charming up to 3 familiars at a time to assist her and turning their effects against Isaac.
 * Isaac's Familiars when charmed retain most of their behaviors when assisting The Siren but can now deal contact damage and block shots.
 * Charmed Familiars have 60 HP and returned to Isaac when killed.
 * If she has less than 3 charmed shooting Familiars from Isaac, she summons up to orbiting 3 Siren Minions of her own. These Familiars behave identically to but with a slower fire rate and can also be killed. She then glides around the room for a few seconds, letting her familiars use their effects against Isaac. If she has any familiars alive after this, she swipes at Isaac, launching all remaining familiars in a cluster in his direction.
 * When the cluster collides with a wall it kills all the Familiars and releases a burst of radial projectiles and a cluster of disorganized projectiles.
 * The amount of projectiles launched during this attack depends on the number of familiars that collided with the wall.
 * Swipes a short distance in Isaac's direction, releasing 5 projectiles.
 * Sinks into the floor becoming invulnerable and chases Isaac, leaving a trail of slowing Black Creep. After reappearing, she swipes at Isaac, shooting a spread of 5 projectiles.
 * Screams, emitting a consistent shockwave around her and spawning 9 pulsating rings of projectiles that expand slowly outwards. These projectiles split into two when far enough.
 * This attack pushes Isaac away like an inverted Gaping Maw.
 * The rings of projectiles have openings towards Isaac's general direction that disappear as the projectiles split.

Upon death, The Siren burns away, leaving behind her skull.

Trivia

 * She is based off of Sirens from Greek mythology, which were dangerous creatures who lured nearby sailors with their enchanting music and singing voices.
 * The Siren is the only boss that can interact with Isaac's collected items.
 * She is also the only boss that can interact with Isaac's familiars.
 * The Siren's ring of tears and sinking in the ground attacks are references to the Gorgun boss from the game Enter the Gungeon. Moreover, both bosses leave behind remains that can be destroyed.

Bug
If The Siren charms the Dead Cat familiar and Isaac dies, the game crashes because Isaac cannot use the extra lives