Or can you do both? This is pre-10 Heart kills. I was thinking that it was an OR, not an AND, and went with the Devil Door even though I still don't have a Mom's Heart win yet on my BOI:R save yet. I'm now thinking I might of wanted the Box instead.

Which then ended up on a crazy run through Sheol, telepill into the I AM ERROR room, down into Dark Room and just about took out The Lamb on my first time ever seeing it. So close and I thought it was completely worth the time seeing new stuff.

Interesting that you can get to the Lamb that early. It's definitely a bummer when you have a powerful run but can't go all the way just because the game wants you to beat the easier parts 20 times first.

Always takes the devil door. The moment you beat mom's heart it counts as a kill so you unlock the ending and whatever item unlock as well regardless of your decision. So you always want to attempt to press further for more unlocks if you can manage it. Later on obviously you'll be able to go into sheol 100% of the time but it's nice being able to make progress on that before beating the heart 10 times.

@spiketail: Edited your thread title. Didn't know about the three things you popped right into your thread title, so thanks for that.

@mb: Ah, my pardons then. 100% unintentional! 10th run overall for BOI:R (1st run was a Mom takedown, 8 failed attempts then my 10th), never got really deep into BOI and couldn't tell you what's new in BOI:R without resorting to a wiki. Or what can be gotten to so early because the RNG decided to allow it to happen.