On this page of Assassin's Creed Valhalla's guide, we suggest how to deal with poison. You will learn what to do when Eivor gets poisoned, when you can be poisoned, how to poison opponents, and how to protect yourself from getting poisoned.
Eivor can usually be poisoned after coming into contact with poisonous green clouds. You may encounter poisonous gas mainly while exploring various types of caves and dungeons. Try to move over poisonous clouds by using high shelves and edges.
If the poisonous gas is impossible to avoid, you can use an alternative method – throw a torch to make the gas explode. It will disappear only for some time, but you will have enough time to safely move forward or to quickly examine the room.
Eivor can be poisoned by enemies if they have the right skills, i.e. weapons that can inflict poison, and bombs that spread poisonous gas. There are two main ways you can react to this - by evading until your opponent's weapon loses its poisonous properties and fighting away from the places where the poison bombs exploded.
This mechanism works both ways – Eivor can also poison their opponents. You can use weapons with the right properties as well as abilities that poison enemies. The most universal poisoning abilities are Poison Strike and Ranged Poison Strike – thanks to them you will be able to poison enemies with melee or ranged attacks. You can unlock them by delivering Hytham medallions of the members of the Order of the Ancients.
If Eivor is poisoned, react quickly by using the rations to heal the character. Otherwise, your hero will gradually lose health points. Ignoring this can seriously weaken Eivor even if they don't receive any other injuries in the meantime.
Additional note - Some of the mushrooms in the game world are poisonous. The hero may lose a lot of health by eating them. Try to rely on "safe" methods of restocking rations, i.e. picking mushrooms that you recognize, or picking fruits from the bushes.