Up to 5-20% Strength based on the charge time of your heavy attacks. Stacks 3 times.
Hitting at least 3 enemies with an attack, restores 12-15% toughness.
Up to 2-5% Strength, scaling with remaining Ammunition. Stacks 5 times.
5-8% Strength for every 10% of magazine spent during continuous fire. Stacks 5 times.