The thing was big, deformed, and angry. I'm not sure if it was trapped until the acid set it free or if it caused the acid to spread or both. In any case, it managed to hit Dworik hard and created some form of anguish to both Ellywick and Phennyr. The latter of which also got physically twisted by its influence. It took many cuts before it fell, though I was preoccupied during most of it.
Dworik and I were caught by the tentacles reaching out from what had first looked like a rock formation. The thing open a maw of very sharp teeth, and it managed to bite us quite a bit before Dworik got his sword into its mouth and Phennyr finished it off.
Phennyr. That's what I should mention before the night is over. The malformed giant made something to him that twisted his body into a deformed version of himself. I had intended to seek some way of restoring him through the gifts of the Raven Queen, but it seems that the effects have faded with his rest. The gnolls are safe, at least two dangers of the cave are gone, and we got a reward. All in all, I think we had a good day. Time to tell Lavia about it while waiting for Thunder to return.