So, I'm working on a Rival... possibly Nemesis that will use a Grasp / Bite / Swallow attack. Biologically, let's use the Sarlacc for comparison. Once it swallows you, you're going to starve to death long before it digests you.
I was thinking of an Escape? ability? Maybe? Athletics (3) or Weapon (2 Advantage or 1 Triump) to escape. The trick is being eaten by the bad guy isn't the problem. It's while you're in its belly you can't stop what the rest of it is doing.