The formula for this potion must be acquired before it can be brewed.
- Brock helps the witcher focus. It increases the effectiveness of all strikes designed to cause of the many critical effects in the witcher's arsenal – Poisoning, Bleeding, Incineration and the like.
- Such close concentration, however, weakens the witcher's defenses. Intent on dealing damage to his foes, the user becomes susceptible to their attacks as his resistances decline. This loss can be counterbalanced by the Golden Oriole potion.
- The potion increases Toxicity very markedly when imbibed.
- Brock is recommended in situations where the witcher has applied an oil to his blade or has specialized in combat employing an additional effect like Incineration.