Black Hole Gun

 is a gun that fires black holes which attract enemies and bullets. The black holes travel slowly across the room until they hit a wall.

Bugs

 * Despite Black Hole Gun not being part of the synergy, firing three Mr. Accretion Jr. planets into the black hole will still cause it to explode and deal 100 damage to all enemies in the room, though it's more difficult due to the black hole's shorter duration and disappearance when colliding with walls.
 * The trajectory of the Black Hole Gun's bullets can be altered by the Lead Maiden, causing them to travel with the Maiden when it is invulnerable.
 * When Lower Case r is duct taped to it, the black hole will not fire if the fire button is released while Lower Case r is in the middle of a word.
 * If two black holes occupy the same spot at the same time, the game will crash. Because of this, it is not advised to use Helix Bullets with the Black Hole Gun.

Trivia

 * The gun's Ammonomicon Entry is a reference to the 1994 song "Black Hole Sun" by the American rock band Soundgarden.
 * The Synergy is a reference to the Lovecraftian Horror genre, which is also sometimes called "Cosmic Horror." Cosmic horror deals with malevolent, godlike aliens affecting our reality in various unpleasant ways, including tentacles coming out of black holes.
 * Another reference might be Rift inducer 5000 from Ratchet and Clank series.