Essential

Serration
Split Chamber
Point Strike
Vital Sense

Central to Build

Hunter Munitions - Slash procs are the focus of this build. Slash procs ignore armour and scales well into late game content.
Viral Damage (Infected Clip + Rime Rounds) - Viral proc synergises well with Slash. At least one 60/60 mod is recommended for improving chance that at least one arrow procs Viral (two is likely overkill). As elemental mods (and IPS mods) do not affect the damage from Slash procs, Prime [Cryo Rounds] will only increase the chance of a Viral proc but not improve Slash proc damage.

Final Slot

Vigilante Armaments - Increases average number of arrows from 13.3 to 17.5. Increases number of slash procs and the chance of at least 1 Viral proc.

More Forma

1 Extra Madurai polarity will allow [Vigilante Armaments] to be replaced with [Heavy Caliber]. [Heavy Caliber] on top of [Serration] will improve the damage of slash procs by 60%+. This outweighs the drawback of less arrows fired on average.