From the current situation, it seems the giant snake doesn't have other physical attack abilities, meaning as long as Jimmy defends against the snake's attack itself, he'd be fine. The rest seems to be illusions affecting Jimmy's judgment, not some high-level ability, so the danger doesn't appear to be great. Then how did Mary and the others have their souls absorbed by the monster?
It couldn't have directly attacked Mary and the others because no one else noticed the monster's attack, and Mary didn't have other injuries. So, this giant snake must have a soul-absorbing ability, but it hasn't used it on Jimmy, which is somewhat puzzling.
Jimmy observed as he retreated, knowing the black mist couldn't cover too much area. This mist would interfere with his Heart Eye Vision, so fighting outside of it would definitely be better.
