Tendriculos

A massive Plant/Fungus creature with a tree-trunk-like center and 20-30 foot vines. It is not friendly or smart, and has a long reach. It likes to eat things and given the opportunity, it will restrain and swallow multiple humanoids whole.
It is immune to acid, poison and piercing damage. It regenerates rapidly when damaged, however fire seems to disrupt its regenerative abilities.
It emits a rather stinky poison which seems to help certain mushrooms grow, including black rattlecaps.