Swallow Whole

Swallow Whole is a special monster attack form found in various roleplaying games, but most associated with Dungeons & Dragons (and by extent its knock-off, Pathfinder), as this was the game that gave it the easily referenced name. Technically, only Dungeons & Dragons 3rd Edition used it as a specific special attack trait, but the ability appeared in Advanced Dungeons & Dragons before that.

As the name suggests, this is an attack whereby a monster can seize a victim - usually an unlucky PC - and swallow them whole and alive. The victim is typically trapped inside of the monster, taking a certain amount of damage per round, but in some editions has the ability to try and cut their way free from the inside. This does not usually kill the predator monster, but it does allow the victim to escape alive and rejoin the fight - most monsters will have the initial wound "magically seal itself" afterwards, so subsequently swallowed suckers must slice their own way out.

As this is literally the defining feature in a vorefag's /d/eviant desires, beware of its appearance in magical realms.