Big Fan

Effects

Spawns a large orbital familiar that blocks enemy shots and deals 2 damage per tick (10 damage per second) on contact.
This item belongs to the Beelzebub set. Collecting three items from this set will transform Isaac into a giant humanoid fly.

The Big Fan is the largest of the orbital familiars, but also deals the least damage. (Added in Afterbirth †) Its contact damage is tied with (Added in Afterbirth †) Bloodshot Eye and its position of the lowest contact damage has been usurped by (Added in Afterbirth †) Mom's Razor while Isaac's damage stat is low.
The Big Fan has lower rotational speed than other familiars (similar to Blue Flies).
The Big Fan orbits independently rather than occupying one of the three defense orbital slots.
Affects the speed of all other orbitals, slowing them down a lot (NOTE: This effect does not happen until you get a new orbital after Big Fan).
Horse pill versions of the Pretty Fly pill spawn a Big Fan without granting it as an item. Big Fans acquired this way spin at normal pace and don't affect rotation speed of other orbitals.

BFFS! / (Added in Repentance) Hive Mind: Big Fan becomes visually larger and deals more damage. Collision radius is not increased, however.

Orbital familiars: If Big Fan is the first orbital obtained, subsequent familiars will match its low speed. (Removed in Afterbirth †) This excludes Pretty Flies.