Santa's Karsolas Pickaxe Build
 Ogryn Build - Warhammer 40k: Darktide 

This is basically a no-brain Karsolas heavy spam build. It's not the most optimal way to use a Karsolas due to FatShark's light vs heavy attack design, despite how satisfying it feels to use.

Still, this build tries to pump up as much damage as possible and let Thrust, Headtaker, and Great Cleaver do all the work to cleave for you.

Do note that the attack speed buffs from Indomitable, Frenzied Blows, and Just Getting Started! do not benefit heavy attacks as much as they do light attacks, but are nontheless taken to gain access to Trample and Great Cleaver.

The combos are:

Mixed Hordes:
Light -> (Heavy -> Heavy) 
(Heavy -> Heavy)
There will often be cases where you may not have enough time to open with a heavy, so a light is used instead.

Single Target (Elite):
Push Attack -> Heavy -> Light
Special -> Heavy -> Light
The push attack and special both utilize a different stagger profile than the standard melee stagger profile, which means you'll have 3 different stagger profiles to pick from to avoid having to deal with the stagger immunity cooldown. These are also the only ways to access the high carapace adm strikedown heavy attack, so keep it handy in your back pocket.

Single Target (Specialist):
Light -> Light
Push -> Light -> Light
Specialists like hounds and trappers are often weak enough, but dangerous enough, to warrent a quicker attack in order to neutralize them with less risk.