Torid Incarnon turns into a chaining beam with a small 2-3meter AOE at site of impact. Innate toxin allows [Rime Rounds] to combine to make Viral with only one mod.

Note: Currently Galvanized Aptitude only applies to the base damage before Final Fusillade/Plentiful Mayhem, meaning it only has a 50% ish effect, and is additive. It also doesnt work on the AOE components of both incarnoff and incarnon.

EVOLUTION GUIDE

Evolution II: Final Fusillade gives +51 damage. The last shot bonus doesn't apply to incarnon mode. The other option Plentiful Mayhem only gives +31 dmg and consumes all your ammo rapidly.
Evolution III: Pick any, but i prefer Swift Deliverance +50% projectile velocity to allow you to hit targets easier for charging of the incarnon form
Evolution IV: Commodore's Fortune - increases CC to 49%, so final CC is 147% with Crit Delay.

MOD BREAKDOWN

Serration/[Amalgam Serration]: This is the OPTIONAL FLEXIBLE slot. If you are happy with no extra sprint speed, use regular [Serration]. If you are happy to rely on merciless stacks only for base damage, swap [Serration] for [Bladed Rounds] or [Primed Firestorm]. Primed Firestorm actually increases the amount of enemies hit by the chaining beams in incarnon mode, not just the AOE of non-incarnon mode.

Galv Chamber: Mandatory multishot
Crit Delay: Mandatory CC
[Vital Sense]: Mandatory CD
[Hunter Munitions]: 30% chance for crit to make slash proc which bypasses armor
[Rime Rounds]: combines with innate tox to make viral. Viral procs boost slash status damage to health by 4.25x. Flexible for [Primed Cryo Rounds].
Vile accel: Boosts fire rate. Flexible for other fire rate mods.

Primary Merciless: Gives +360% base damage and can proc on slash DoT kills.

RIven
Positives: MS, CD, CC, FR, DMG
Can slot over [Serration]
Slot over Vile accel if roll FR
Slot over Crit Delay if roll CC

VARIANTS

Without a primer or armor strip, use pure Raw Corrosive: for grineer/corrupted, acolytes, thrax without armor strip. Swap Hunter Munitions and Rime Rounds for Stormbringer + Galvanized Scope or Bladed Rounds. https://overframe.gg/build/499031/

Without a primer but WITH armor strip, use pure raw Viral: Swap [Hunter Munitions] and [Rime Rounds] for [Primed Firestorm] + [Primed Cryo Rounds].
OPTIONAL: Can swap Crit Delay for [Galvanized Scope] if you can hit heads, Serration for Bladed Rounds and Primary Merciless for Primary Deadhead. This is the highest possible DPS against Grineer/Corrupted if using armor strip, without a primer.

With armor strip, priming and [Galvanized Aptitude] + Primary Blight, use pure toxin for the highest possible DPS out of all options:
Pure Toxin + toxin DoT (for armor stripped grineer/corrupted/corpus with a primer): Swap [Hunter Munitions] and [Rime Rounds] for [Infected Clip] + Galvanized Aptitude, swap Vital Sense for Hammer Shot and use the new Primary Blight arcane. Change Evolution IV to Survivor's Edge. https://overframe.gg/build/492817/torid/pure-tox-torid-incarnon/. This is the highest possible DPS if using both armor strip and a primer. Good for both Corpus and Grineer/Corrupted (doesn't need armor strip in early levels, but may need it in later SP Levels). Beams are especially good at applying status DoTs such as toxin because status damage double dips multishot on beams. You can also combine this with Expedite Suffering to trigger all toxin DoTs at once to basically 'oneshot' any enemy.

For Murmur/Whispers update: https://overframe.gg/build/572414/
For Gargoyle's Cry even against Fragmented: https://overframe.gg/build/572820/