Bank Demons are a kind of demon that's usually resides at the banks of rivers. They are often called "Froggies", because they resembles gigantic flying frogs. The mouth is large enough to swallow a human whole, and it is filled with rows of small, sharp teeth. When they locate a human they try to catch the victim with their tounge, if they miss they will jump out of the water and try to catch it again. If the human struggles after the catch the Bank Demon will drag the victim under the water and drown him or her.
Their arms: they have only short claws so they are unable to make melee attacks, if you get near enough, you can kill them with a good spear.
Water: They need water to live, without water they can't form themselves.