Blizzard is one of the most powerful witchers' potions; it improves reflexes and reaction time, allowing a witcher to better parry and evade attacks. It slows down time, making Geralt's movement and everything else slower. It is most helpful against groups of enemies and monsters that move fast or teleport, such as wraiths and various types of vampires.
Added to Gwent
[Feb 06, 2017] Major Update - Nilfgaard Arrives.
[May 24, 2017] Major Update - Public Beta, split Blizzard Potion's Immune Boost and Overdose to 2 separate cards.
- See this subject on The Witcher wiki: Blizzard