The word 以毒攻毒 is formed by the sequential combination of four characters: 以 (meaning "use" or "with"), 毒 (meaning "poison"), 攻 (meaning "attack" or "combat"), and 毒 (again meaning "poison"), resulting in a literal structure where the first 毒 is the means and the second 毒 is the target, directly translating to "use poison to attack poison".