The Engorged was a fun boss encounter in The Astral Academy.
The idea behind it was a predatory creature that lived on a landscape that only wandered undead - the creature would consume necrotic flesh for sustenance.
This was made with Duqazhan in mind who may use their gravity magic to adjust the weight. This would reward with a weaker Seismic Wave - but it ended up not being used.
The Bite was to be a terrifying realization that this not a creature to be in melee with. I added a side rule swallow just before the battle so the stats aren't here - however, you could easily make it so that if you wanted to swallow creatures, you can have it regurgitate the creature if 50 points of damage is dealt (or 20 points of damage is dealt total to The Engorged Stomach, which could be aimed - by the raised AC would be 18)
Fun question : What is more dangerous - 1 attack that deals 8d12, or 8 attacks that deal 1d12? Answer: The 8 attacks that deal 1d12. While you have to check on each attack if they hit - if you decide that creature attacks a downed player, they are instant KO'd from the multitude of attacks - completely bypassing Death Saving Throws. Be mindful when using multiple attacks with creatures.