Well, that's pretty much exactly how the Remhoraz's Swallow attack works, by the MM2. Deal 30+ damage with a single attack, it spits you up. Otherwise, at the start of the Remhoraz's turn, you take 10 untyped damage and another 10 fire damage.
Out of curiosity, are you the DM, or a player?
It just seemed to me like a question a player might ask.
Either way, the rules got ya covered.