Wizards Unite Focus has two different types in Harry Potter: Wizards Unite: Initial Focus and Maximum Focus. Focus is basically like mana in other spell casting games.
Players use Focus to cast Hexes and Charms during Fortresses.
Wizards Unite Focus Explained
Each Profession has a different starting point, but each Profession has skill tree nodes that will increase your Initial Focus or Max Focus Capacity. You can also use potions to increase your focus during fights. Every time you defeat an enemy, you earn back more focus. So you can start a fight, use focus to attack an enemy, beat them, then gain the focus back for the next level of the Fortress.
Aurors are the only ones that can share Focus between players.
You can learn the full skill tree through some amazing guides that break down the increase in Focus in the different nodes.
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