Adder

As the only poisonous snake in the British Isles the adder has a reputation for wisdom, reincarnation, and cunning. The amulets said to have been carried by the  druids, 'gloine nathair' (the glass of the serpent), were really adder stones. If you see a snake while Faerie Vision Questing, be prepared for the power of transformation to enter your life. The snake represents the life-death-birth cycle. It was an adder which caused the Battle of Camlan; while the armies of Mordred and Arthur were drawn up during a parley in which the battle might have been averted, an adder darted out from the scrub, so startling one  of Arthur's men that he drew his sword to slay it. Taking the flash of his sword as an instance of Arthur's treachery, Mordred's army attacked. In the Highlands, the adder or serpent is supposed to represent the CAILLEACH'S power, which Brigit defeats with her lamb.