Remorhaz

At the end of each of the monster's turns, each in a -foot Emanation originating from the monster takes damage.

. . If the target is a creature, it has the Grappled condition (escape DC ), and it has the Restrained condition until the grapple ends.

Strength Saving Throw: DC , by the monster (it can have up to two creatures swallowed at a time).
Failure: The target is swallowed by the monster, and the Grappled condition ends. A swallowed creature has the Blinded and Restrained conditions, it has Total against attacks and other effects outside the monster, and it takes damage at the start of each of the monster's turns.
If the monster takes 30 damage or more on a single turn from a creature inside it, the monster must succeed on a at the end of that turn or regurgitate all swallowed creatures, each of which falls in a space within feet of the monster and has the Prone condition. If the monster dies, any swallowed creature no longer has the Restrained condition and can escape from the corpse by using 15 feet of movement, exiting Prone.