10-16 Bleed Stacks from Special Attacks.
Hitting an enemy gives them 1-4 stacks of 2.5% Brittleness. Debuff lasts for 5 seconds and can have a maximum of 16 stacks.
3.5-5% Critical Chance for every 10% of magazine spent during continuous fire. Stacks 5 times.
4.25-5% Strength for every Enemy you Stagger. Stacks 5 times.
Playstyle: fast run and gun. ADS for extra stagger. Always be sprinting and sliding toward enemies to close distance and proc Skirmisher (up to 20% base damage), Reciprocity (up to 25% crit chance) and Duck and Dive (30% stamina).
Shredder has high stagger so will interrupt any specialist attack (trappers, dogs, bombers, etc). Shredder is great for ragers, maulers, elite gunners, specialists.
It needs as much crit/damage boosts as possible though because base damage is pretty bad. Opening Salvo (10% crit for first 20% mag after reload) is great for this gun because reloads are fast. Pinning Fire gets max stacks almost immediately shooting the same target (you don't have to stagger multiple targets to get max stacks).
Chaxe for Orgyns/Monsters/Mutants with revved attack.
Build is weakest for horde clearing. For hordes, mix in lots of grenades (Demo Stockpile & Demo Team should give around 60+ grenades per match) and VOC. Use heavies and push attack on Chaxe when necessary.
