Deadfly
Deadflies are large, holy flies that are found in the Cathedral that float very slowly after Isaac and are orbited by 3 
Eternal Flies. If there are any other enemies in the room, they will spawn an Eternal Fly for them, with a maximum of 1 fly orbiting each enemy. After spawning an Eternal Fly for each enemy, or there are no other enemies in the room, they will alternate between first spawning 3 
Attack Flies and then spawning Eternal Flies to orbit each of those Attack Flies.
If Isaac gets too close to a Deadfly, it will become enraged and begin quickly flying diagonally, bouncing off of walls and directions. While flying, they will rapidly fire out homing projectiles in random directions. After a period of enragement, they will calm down and resume their normal pattern.
Notes
- Enemies that already have Eternal Flies such as
Hangers or 
Danglers will still be able to be targeted by the Deadfly, bringing them up to 2 Eternal Flies.
Gallery
A Deadfly spawning other flies.
An enraged Deadfly.
Concept art for Deadfly.
"Primordial" (old) concept art for Deadfly.
