Somehow I was taking 1 full heart of damage from enemies (Pre womb)

[Spyro]

I thought it was something about the bone heart not being full or something, because I went into a curse room with 1 full bone heart and it broke instantly. And then when I had 1 full normal heart left, I got hit by a basic grub enemy and died instantly?

[Drunken Duck]

i don't know about the situation with bone hearts, they break if you take damage and they're empty. maybe you missed it and it was in fact empty, maybe you had golden heart (which doesn't add a layer of protection, it just has effect on breaking). maybe you had some item or trinket influencing, although i can't think of any that could do this.

pre womb you take full heart damage in these cases:
getting hit by champion enemies (they're of different colors/sizes)
getting hit by specific enemies, which always deal one full heart of damage (globins are the main ones). explosions also usually deal full heart damage
getting hit under the influence of addicted! pill (the pill makes you take 1 heart of damage for 1 room)

[Spyro]

Originally posted by Drunken Duck:

i don't know about the situation with bone hearts, they break if you take damage and they're empty. maybe you missed it and it was in fact empty, maybe you had golden heart (which doesn't add a layer of protection, it just has effect on breaking). maybe you had some item or trinket influencing, although i can't think of any that could do this.

pre womb you take full heart damage in these cases:
getting hit by champion enemies (they're of different colors/sizes)
getting hit by specific enemies, which always deal one full heart of damage (globins are the main ones). explosions also usually deal full heart damage
getting hit under the influence of addicted! pill (the pill makes you take 1 heart of damage for 1 room)

Hmm weird, I definitely had 1 full heart and only got hit by this https://bindingofisaacrebirth.fandom.com/wiki/Maggot

I had no pill used on the room so can't be addicted

[Drunken Duck]

then it should have been a champion enemy. it could be invisible or changed in color so slightly that you didn't notice them being not like others. or maybe some super rare situation, if you remember your trinket(s) and items?

[kone]

The only other thing I can think of is Glass Cannon.

Even if it doesn't break from self-damage, do you remember if you've taken damage from another source before entering/leaving one?
That item is the only item from the top of my head that can remove a filled bone heart without outright killing you. Also maybe explains taking massive damage from a non-champion Maggot enemy.

[Drunken Duck]

that makes sense! you take 2 hearts worth of damage when you take damage with non-broken glass cannon. an empty bone heart can be lost in that case as a part of excess damage. however you can't die because of excess glass cannon damage

[levijamesfred]

champian

[Diego]

Did you pick up rotten hearts ? The ones that are covered in grease or mold or whatever it is. They make you spawn 1 fly upon entering a room but in exchange they act as half a heart. But visually they look like a full heart.