Recover 15-24% toughness when hitting an enemy with a heavy attack, based on charge time.
Up to 5-20% Strength based on the charge time of your heavy attacks. Stacks 3 times.
Gain 7-10% Close Damage for 3.5 seconds after killing an enemy at close range, stacking 5 times.
1-4% Toughness for every 10% of magazine spent during continuous fire. Stacks 5 times.
This build is made for penance called Don't stop me now!
In the Youtube video you can find 2 ways how to do it.