When using with [Gauss] or [Harrow], consider swapping [Serration] for [Primed Magazine Warp]

Mod [Overview] and alternatives:

Damage : [Serration] or [Amalgam Serration]. Amalgam provides [Sprint Boost] for quality of life with minimal drop in damage. Bonus additive damage comes from primary merciless. Do NOT stack [Heavy Caliber] on top of [Serration] since you get diminishing returns. Do NOT use [Galvanized Aptitude] as this is not working with AOE as of this patch.

Multishot: Galvanized Shamber or [Split Chamber].

Critical chance: [Critical Delay] or [Point Strike]. [Critical Delay] provides more consistent crits and the fire rate penalty doesn't affect Zarr that much.

Critical damage: Vital Sense.

Slash procs: Hunter munitions - allows slash procs that bypass Grineer armor

Viral: Rime rounds or primed cryo rounds - combine with innate toxin to make viral. [Rime Rounds] allows more consistent viral procs which boosts slash proc damage. [Primed Cryo Rounds] provides higher base damage but best used with external source of viral e.g. panzer vulpaphyla.

Faction mod: Primed bane or regular bane of Grineer - double dips on slash procs by increasing base damage and slash proc damage

Flexible slot: [Primed Firestorm] to increase range, [Hammer Shot] to increase CD and status, [Primed Fast Hands] to improve reload, [Vile Acceleration] to increase fire rate

Exilus: [Vigilante Supplies] gives ammo to the small ammo pool and also has a 1 in 20 chance to boost a shot with +100% additive crit chance. Ammo mutation is fine as alternative. [Cautious Shot] if you have no other way to negative knockback, but not ideal since there is still a stun involved when fired at close range.

Arcane: Primary merciless

Anti-corpus build: https://overframe.gg/build/205451/kuva-zarr/kuva-zarr-anti-corpus/