'Twisting vine serpent
The bloodline of this vine serpent has changed through various processes while living in a venom and poison steeped environment. As this was the case, it developed better abilities to consume and camouflage with the jungle itself. Its body had a layer of dense bark acting as scales which are extremely tough to break through.
With its toughness defenses, the body is able to grow much larger and resist the many other monsters capable of delivering poisons or venoms through touch or other means of attack. This has allowed for it to also resist the many plants which it would normally have been poisoned by.