A werewolf is a wolf.
A werewolf is a human that can turn into a wolf. A werewolf has been scratched or bitten by another werewolf. If someone has been scratched or bitten, they have been attacked.
∀x (Human(x) ∧ CanTurnInto(x, wolf) → Werewolf(x)) ∀x ∃y (Werewolf(x) → (BittenBy(x, y) ∨ ScratchedBy(x, y)) ∧ Werewolf(y)) ∀x ∃y (BittenBy(x, y) ∨ ScratchedBy(x, y)) → AttackedBy(x,y)