Beelzebub

Isaac turns into a giant humanoid fly and gains flight. While in this form, most types of enemy flies will automatically be converted into Blue Flies. Enemies such as Boom Fly and its variants will become friendly and be brought with Isaac to other rooms and floors.

Requires any combination of three of the following items to be collected:

Passive Collectibles
Repentance only:

Trivia

 * Beelzebub is the name of a Demonic fly who is known as "Lord of the flies" and is known as one of the 7 princes of hell. Beelzebub is also another name for the devil.
 * In modern Catholic tradition, Beelzebub is regarded as one of the 7 princes of Hell; however, the origins of the name Beelzebub actually dates back to an early Jewish insult for worshippers of a Canaanite Deity Ba'al 'Lord', or Ba'al-Zvul 'Lord of the manor/dwelling', calling him Ba'al-Zvuv, 'Lord of the flies'.
 * The achievement 'Lord of the Flies' is a reference to this.

Seeds
W2DW TA79 (Allows Isaac to become Beelzebub in The Caves XL. First two Treasure Rooms are Big Fan and Attack Fly, one of the Treasure Rooms in Caves XL is Halo of Flies) 9CM4 JDBL (Last fly item collected on Flooded Caves I) B14A Q44Y (Also contains four Guppy items) TF11 R19Z (First three floors Treasure Rooms contain Smart Fly, Forever Alone, and Infestation)