Famous Flamer - Penetrating Flame
 Zealot Build - Warhammer 40k: Darktide 

Who knew a Zealot with a Flamer and a plan for Carapace armor could be fun for the whole team? Penetrating Flame on the flamer (and Inferno Staff for Psyker) has a separate 20% brittleness from conventional brittleness stacks (which cap at 40%) and so whether it's you or a friend bringing Thunderous or another source of Brittleness, you'll be able to amp up monstrosity and crowd kills even more powerfully.  Catachan knife with Flesh Tearer and Ruthless Backstab is a great combat axe alternative - I like the Mk6 knife for the sweeping heavies.  Brutal Momentum can be used on the axe instead of Shred if you want though the flamer takes care of most things you'd be using Brutal Momentum for.  All 3 combat axes can be used, the Antax and Rashad are easiest to not miss with.  Blaze Away or Inspiring Barrage on the flamer is better for general use than Showstopper and Showstopper's on there because it's funny to see booms.  Curios are flexible to your needs.