Does taking no red heart damage not guarantee a devil/angel room?

[Soup Eater]

I have just beaten mom's heart 5 times, and only gotten to Sheol once (did not beat Satan). I have had several rooms where I took no red heart damage on womb 2, but still got no devil/angel room. The wiki says taking no red heart damage adds +99% chance to your 1%, wouldn't this mean an 100% chance of a devil/angel room?

[Nazemec]

That's not how the percentage is calculated actually. It starts at some value (not always 100%, depends on wether or not you had a Deal on the previous floors) and decreases each time you get red heart damage (decreases even more if you're hit during the boss fight).
(Checked using MissingHUD2.)

Anyway, don't rely on Devil/Angel rooms to go to the 9th floor. Kill the Heart 11 times and you'll get a permanent access to both Sheol and the Cathedral (unaffected by your Deal room chance).

[burn1none]

Seems when Afterbirth came out that taking any damage hurts your chances but taking red heart damage nearly guarantees you won't get one. I think there are mods you can download to see how much each affects your chances

[Soup Eater]

Originally posted by burn1none:

Seems when Afterbirth came out that taking any damage hurts your chances but taking red heart damage nearly guarantees you won't get one. I think there are mods you can download to see how much each affects your chances

I don't have afterbirth sadly, I currently only have rebirth.

[Roarak]

http://bindingofisaacrebirth.gamepedia.com/Devil_Room#Deals_with_the_Devil

Taking no Red Heart Damage will increase the spawn chance to 100% but if you've recently seen a deal room the % chance of one appearing is reduced, divided by 4 if you got one last floor, and divided by 2 if you saw one in the last 2 floors.

[Soup Eater]

Originally posted by WTFohitsyou:

http://bindingofisaacrebirth.gamepedia.com/Devil_Room#Deals_with_the_Devil

Taking no Red Heart Damage will increase the spawn chance to 100% but if you've recently seen a deal room the % chance of one appearing is reduced, divided by 4 if you got one last floor, and divided by 2 if you saw one in the last 2 floors.

Oh, ok, thanks! I had a devil room practically every other floor that run.

[brickey.8]

I remember reading that there's a special case where taking no damage (or any kind) against Mom's heart while you don't have It Lives unlocked will guarantee a devil room, just to allow you to sequence-break into Sheol, but I don't know if that's true.