The Fallen

The Fallen is a rare boss added in the Halloween Update. He looks like a regular demon, with shiny red eyes, horns, black wings, and an upside-down cross (Cross of St. Peter) on his forehead. His body ends with a nubby tail section.

Behavior

The Fallen has two phases and three attacks.

1st Phase

The first consists of him chasing after Isaac at high speed. He will stop after taking enough damage and unleash his second attack, launching 4 blood beams (similar to Brimstone) in cardinal cross directions.

2nd Phase

For his last attack, he'll spit two salvos of bullets, one with 3 and the other with 4. When his HP reaches 50%, he will enter his second phase, splitting into two smaller Fallens, each with the same attacks as the original.

Strategies

The Fallen may appear intimidating, but as his patterns are very predictable; he can be killed with relative ease. The projectile waves that he shoots can be dodged easily by weaving in between the bullets or just moving to the side. In phase two, when there are two smaller Fallens, it is best to kite them around the edges of the room during their charge attack.

If Isaac has The High Priestess Tarot Card it is possible to defeat the Fallen in one hit simply by using the card. Mom's foot will kill both the original Fallen and the two smaller Fallen immediately as they spawn, finishing the fight almost instantly.

Champion Variant

In Hard Mode, the Eternal Fallen splits into three of itself at half health, with one of the Fallens appearing slightly larger than the other two. The larger one has slightly stronger firepower, the other 2 smaller ones are identical to a normal Fallen.

This variant was added in Eternal Edition.

Notes

The Fallen is also part of the first phase of the battle against Satan.
The Fallen will always drop a Devil Room Item when he is encountered as a boss.

Trivia

The Fallen has many similarities with Isaac's diverse demonic appearances.
Its name is most likely a reference to the fallen angels that followed Satan, in keeping with the Biblical themes of the game.
In the credit sequence, The Fallen is misspelled as "The Fallin."
According to Edmund, it is possible to find a champion version of The Fallen, but it's extremely rare.^[1]
- However, this is actually incorrect, and no champion version of The Fallen exists in the game.

Bugs

If The Hourglass is used while The Fallen is splitting, he will split into 4 instead of 2.
If you have Dead Bird and it is attacking The Fallen before he splits, when he does split the dead bird will disappear until the next floor.
Sometimes when fighting The Fallens's two smaller parts, they will teleport to opposite ends of the room. This only seems to happen when being encountered in a non-boss room.
When you use Best Friend while The Fallen is splitting if the explosion hurt one of the little Fallen while he hurt you, the game freeze.