The Ritual
The Ritual is a Boss added by The Ascent of Isaac Godmode that can be found in 
Sheol.
It is the alternative final boss of the floor, having a 50% chance to replace 
Satan.
Behavior
Phase 1
The Ritual moves slowly around the center of the room and will mainly attack through its 5 candles orbitals. Isaac cannot damage The Ritual while it is attacking. It randomly does the following 4 attacks:
- Places 4 candles at the corner of the room and one in the center, then brightens 2 candles before shooting a line of flames between those.
- Makes all candles orbit around Isaac. One of the candles will brighten before shooting a fire projectile towards Isaac. It will do that multiple times.
- Randomly places the candles in the room. The candles will then alternate between moving randomly twice when being blue and dashing towards Isaac when being red.
- Summons 1
Silent and 2 
Mums.
Phase 2
After The Ritual has its HP reduced to 75%, one of its eyes will become blue and it performs the same attacks as before, but they are buffed:
- The flame line attack happens between 3 candles instead of 2.
- The Isaac orbiting attack is faster.
- The candles dash towards Isaac further and faster.
- Summons 3 Mums instead of 2.
Phase 3
After The Ritual has its HP reduced to 50%, its other eye will become purple and its tail will get a flame. It buffs its attacks again:
- The flame line attack happens between 4 candles instead of 3. To help avoid the attack, The Ritual will extinguish the unused candle before activating the other ones.
- The Isaac orbiting attack is faster.
- The candles dash towards Isaac further and faster.
- Summons 4 Mums instead of 3.
Phase 4
After The Ritual has its hp reduced to 25%, a large flame will appear inside the hole in its forehead. It buffs its attacks one last time and gain a new attack:
- Makes the candles orbit clockwise closer to it and shoots purple flames in front of each candle while regularly shooting 5 large purple flame projectiles itself.
- The flame line attack happens between all the candles instead of 3.
- Summons 5 Mums instead of 4.