Attack of opportunity

An attack of opportunity is a chance for Geralt's opponents to attack him while he is otherwise occupied during combat. In the case of ranged attacks, this is most likely during the "power up" portion of the attack. In the case of potions, it is quite likely during the time it takes for Geralt to use a potion if he does so during the actual battle.

Specifically, on "Hard" mode, Geralt's enemies make full use of these opportunities to attack him, making the combat in the game more difficult. For "Easy" or "Normal" modes, they do not.