Abilities play a crucial role in Assassin’s Creed Valhalla when you are outnumbered by enemies. Not only does it help in taking out more enemies quickly, but it can also prove to be quite beneficial in defeating stronger enemies as well. While abilities can be unlocked by getting Books of Knowledge scattered across the world, you can’t use abilities whenever you want.
To use abilities, you need to have enough adrenaline. Adrenaline is the small yellow bar just above your health bar. Adrenaline increases by doing a number of things. Not only does it increase by defeating enemies and successfully parrying, consuming certain kinds of food scattered in the game’s world such as Blackish Purple Ursula instantly fills your adrenaline bar.
At the start of the game, you get only one adrenaline slot which can prove to be insufficient once you start facing stronger enemies. The only way to increase adrenaline slots is by getting more skill points and getting the extra adrenaline slot skill. You can get more skill points by leveling up in the game. As you defeat enemies and complete quests, you get XP which increases your level.
You get two skill points every time you level up and these can be used to unlock the skills. As you progress through the skill tree, you will find a number of nodes marked with the adrenaline bar, and unlocking those will increase your adrenaline slots.