Fury is a single-player ability first unlocked in Chapter 2 by picking up a Purity Seal, and later upgraded by collecting further Seals.
When the initial ability is unlocked, the player starts accumulating "Fury" every time they damage an enemy. When the Fury meter is filled, they can enter the Fury mode (default key is T), gaining more effective melee attacks and regenerating health constantly. The Fury meter will start draining once the mode is active, and when it is empty, the Fury mode ends. Later upgrades grant duration/charge improvements and buffs to ranged attacks.
Fury Mode[]
The basic Fury Mode is unlocked in Chapter 2. When activated, it grants more effective melee attacks and health regeneration. Enemies that require stunning to be Executed may be Executed instantly while Fury is active.
Fury Mode can be used to defeat a large mob in melee (winning the fight through constant regeneration and buffed damage, when it would be suicidal normally) or emergency healing; the Fury health regeneration doesn't require fighting to work, so Fury healing can be used while safely in cover.
Marksman Mode[]
The Marksman Mode is a Fury upgrade collected at the end of Chapter 3. After activating Fury, the player can enter a slow-motion sniper mode by using the aim/zoom key. Weapons will generally have a faster rate of fire and higher damage during Marksman Mode. Fury will drain and run out as normal. Marksman Mode cannot be used with exotic/mounted weapons (Heavy Bolter, Plasma Cannon, etc.)
Superior Fury[]
Superior Fury is a Fury upgrade collected in Chapter 7. It will make the Fury meter drain much slower, granting prolonged Fury mode.
Supreme Fury[]
Supreme Fury is a Fury upgrade collected in Chapter 10. It will make Titus accumulate Fury faster, allowing more frequent Fury activations.