Does a character who has been swallowed whole treat
the swallowing monster as flat-footed?
The Sage thinks that’s a reasonable interpretation. The
“swallow whole” entry on page 315 of the Monster Manual
indicates that the AC of the interior of a swallowing creature
has “no modifiers for . . . Dexterity.” While this isn’t
necessarily quite the same as saying that the monster is denied
its Dexterity bonus to AC, it’s pretty close.
In addition, it certainly seems true that the swallowed
character has total concealment from (i.e., is “invisible to”) the
swallowing creature, which would allow the character to treat
the creature as flat-footed against his attacks.
Put together, this means that letting the rogue get gulped
might make an effective way to defeat a swallowing monster . .. assuming the bite and ongoing damage doesn’t kill her.
根据这个FAQ,说明怪物是可以从内部击破的