Overview
Now I all know you guys know that you can’t take red heart damage on the floor in order to get a devil or angel deal. What this guide is for is giving the specific chances of a devil room or an angel room on any floor from Basement II – Womb II
Devil Room Chances
The Devil Room has a chance to appear after defeating a boss in the floors between and including Basement II – Womb II. It usually contains a different set of items each time in which Isaac can do a ‘deal with the devil’, by trading health containers for collectable items. By taking a devil deal, this also makes it impossible to find Angel Rooms later in the run.
The chance for a Devil Room door appearing on a floor can be manipulated by meeting a set of criteria. Your percentage chance of seeing the devil room goes down if you take red heart damage on the floor, and can increase by having certain items. By default your lowest possible chance is 1%, then additionally the following conditions can lower/increase that chance:
CONDITION PERCENTAGE (%)
Not taking red heart damage on the entire floor – +99%
Not taking red heart damage on the boss fight – +35%
Holding the Book of Belial – +2500% (not a typo)
Holding Goat Head – Guaranteed
Holding Book of Revelations – +25%
Killing a regular beggar – +35%
Killing a dead shopkeeper on the floor – +10%
Holding Pentagram – +20%
Holding a second Pentagram – +10%
Holding Black Candle – +30%
Saw a Devil/Angel room on the previous floor? – Percentage / 4
Saw a Devil/Angel room 2 floors ago? – Percentage / 2
Combining the above conditions will give you your final devil/angel door percentage chance. By default, after meeting the conditions for an angel room to appear, you have a 50/50 chance of the door that spawns being either a devil or angel room. If you have not yet met the angel room conditions or have locked in your devil deals by taking one, it will always be a devil room door.
NOTES:
The devil room can also contain 3 red chests or the Krampus boss fight (10% chance of Krampus, jumping up to 40% if you have already taken a devil deal)
It is recommended that you enter the Devil Room as soon as the door appears, due to the fact that your percentage chance is re-evaluated again the next time you exit and re-enter the boss room. The 0.25 multiplier for seeing a devil room on the previous floor is also applied at this moment, meaning your chance is much lower than the first time it was checked.
The Book of Belial and Goat Head always guarantee a devil deal and force the door to stay open, however the Goat Head and The Book of Belial have the additional bonus of being able to open a devil door even if it was closed the first time around.
Exploding a normal beggar gives an extra +35% chance for the door to open, however all other beggars only count towards increasing the chance of Angel Rooms in favour of devil rooms.
There are other methods of entering the devil room, such as a Joker card or being teleported by a Red Chest.
Soul hearts are extremely useful for getting devil rooms as they provide a buffer that can stop you taking red heart damage, which would reduce your percentage significantly.
Demon Beggars, Blood Donation Machines, IV Bag, Blood Rights, Razor Blade do not count as taking red heart damage.
You are guaranteed to see a devil room on Basement II if you take no red heart damage on the entire floor. This means Blue Baby will always see a devil room on Basement II.
Angel Room Chances
Angel rooms are the alternative option to the Devil Rooms which can spawn after defeating a boss. Angel rooms can contain a free item from the angel room pool, spirit hearts or eternal hearts. They have a chance to replace devil rooms if the following 2 conditions are met:
You saw a devil room door spawn at least once on a previous floor.
You did not pay for a devil deal with health.
If those two conditions are met, any future devil room doors have a 50% chance to be replaced with an Angel Room instead… however that 50/50 devil/angel split can be weighted differently by doing certain things in the game.
ALTERING THE ANGEL ROOM GENERATION CHANCE
Normally the chance to find an Angel room instead of a Devil Room is 50%, however this can be altered by gaining the following bonuses
WEAK BONUSES
Killing a Devil Beggar, Key Beggar, or Shell Game Beggar in the Arcade
Holding Key Piece #1
Holding Key Piece #2
STRONG BONUSES
Holding the Rosary Bead trinket
Donating 10 coins to the Donation Machine on the current floor
Players can have a maximum of 2 strong bonuses and 3 weak bonuses on a floor. The combined chances are as follows:
0 STRONG BONUSES 1 STRONG BONUS 2 STRONG BONUSES
0 Weak bonuses 50% 75% 88%
1 Weak bonus 63% 81% 91%
2 Weak bonuses 72% 86% 93%
3 Weak bonuses 86% 89% 95%
NOTES:
Contrary to popular belief, the Bible Tract trinket doesn’t allow Angel Rooms to appear after paying for a Devil Deal.
The bonus from killing a beggar can only be applied once per floor and does not stack.
The donation machine bonus needs to be donated all in one go and will only apply for the current floor.
Taking Red Chest items, using the Credit Card, or collecting an item from Krampus doesn’t break the conditions for being eligible for Angel Rooms.
Devil deals taken from a black market will lock in your devil deals and make getting future Angel Rooms impossible.