Samael
Samael is the only mini-boss added in Retribution. Samael is the third Angel after File:Uriel.png Uriel and File:Gabriel.png Gabriel.
In order to fight Samael, Isaac must summon Uriel and Gabriel first, either by bombing Angel Statues in the File:Angel Room.png Angel Room or by stepping on the spikes in the 
Sacrifice Room enough times. Once Isaac attempts to summon an Angel for the third time, Samael will appear in place of Uriel or Gabriel.
Once Samael has been defeated after being summoned, he will spawn 
Jet Feather instead of File:Key Piece 1.png Key Piece 1 or File:Key Piece 2.png Key Piece 2. Afterwards, Samael will have a 1/3 chance of appearing again when summoning another Angel, but he will not drop another Jet Feather when defeated.
Behavior
Samael moves towards Isaac, and attempts to position himself above Isaac while doing so. He stops moving and folds his wings to perform the following attacks:
- Releases a ring of 12 scythe projectiles which rotate outwards, clockwise.
- Gazes skyward with his wings raised, summoning a Samael Angel with a maximum of 2 alive at once.
- Gazes skyward with his wings outstretched, causing all Samael Angels in the room to create 4 short-ranged dark-colored File:Revelation.png Revelation beams in either the cardinal or ordinal directions, based on their appearance.
- Samael can only perform this attack while there is at least one Samael Angel in the room, and Samael Angels will not shoot projectiles during it.
Samael deals a whole heart of contact damage.
Spawns
Samael Angel
Samael Angels are a skeletal variant of File:Angelic Baby.png Angelic Babies that can only be spawned by Samael. Samael Angels act identically to their counterpart, though their spread of 3 projectiles will look like bones, and they have a 50/50 chance to either have regular eye sockets or X-shaped eyes.
When Samael performs his beam attack, Samael Angels with normal eyes will create 4 short-ranged beams in the cardinal directions, while those with X-shaped eyes will fire 4 short-ranged beams in the ordinal directions. After performing this attack, Samael Angels will teleport to another location in the room.
Trivia
- Samael is an archangel in Talmudic and post-Talmudic lore, being heavily attributed to the themes of destruction and death. Many of his functions have been compared to that of Satan in Christianity, and some interpretations has labeled him as a fallen angel. The name means "Venom of God".