@JeremyECrawford does being inside of a creature (swallowed whole) change that creature’s AC?
— Denis Hoffman (@curbstompt13) June 6, 2016
A monster's swallow ability specifies its game effects. There's no general rule about swallowing. #DnD https://t.co/49UFD4NgBQ
— Jeremy Crawford (@JeremyECrawford) June 6, 2016
@JeremyECrawford I'm inside a creature and my buddy hits it w/ lightning bolt. Am I considered "in the line?" #NoGeneralRuleAboutSwallowing
— Colin Stricklin (@ColinStricklin) June 6, 2016
Example: the purple worm's Bite action says that a swallowed creature has total cover against effects outside. #DnD https://t.co/kAxSrayqg8
— Jeremy Crawford (@JeremyECrawford) June 6, 2016
@JeremyECrawford so the inside of a creature has the same AC as the outside of a creature?
— Roger Chong-Yi Lee (@yperil) June 7, 2016
A swallow ability would tell you if the swallower's AC was different on the inside. There's no general rule. #DnD https://t.co/ULyWeteSvI
— Jeremy Crawford (@JeremyECrawford) June 7, 2016
Once my players fed a Necklace of fireballs to a roper. I couldnt justify it surviving so i just ruled that creatures were ‘vulnerable’ to attacks from within themselves. It worked a treat – the roped exploded messily all over the cavern.
If you could count the stomach as a dex 0, unarmored part of the body, it would be AC 5. As for damage too it, perhaps the creature could make a con check, DC 8 + damage dealt, to not ‘throw up’ the contents of its stomach. Otherwise i would say it was vulnerable to damage but immune to acid. Given the swallowed adventurer is restrained, blinded, prone and suffocating they can still attack at disadvantage. shouldnt be too hard to get a dagger and just start stabbing.
Still though, if its big enough to swallow live prey its probably evolved a harder stomach lining.. at your discretion ofcourse, like a rock worm probably wouldnt have a soft stomach lining, so perhaps something to the tune of AC 16 would be more appropriate.
Just my thoughts
Thank you Noble Chris.