Instructions
Stop moving as soon as you land in the vine room. Ron will already be wrapped up in vines.
Cast Lumos to clear out any vines from around you.
Stand still in the middle of the room and shoot your want out at the vines holding Ron, as well as any other vines coming from the floor. It may take several shots to kill the vines, but once they are gone, Ron becomes free.
Drop down through the hole in the ground to proceed to the next puzzle, once Ron is free.