-This is a build for the beam mode of Incarnon upgraded Atomos (currently the best secondary AoE beam in the game).
-For buffed shields Corpus, toxin kills faster: https://overframe.gg/build/491573/.

-Incarnon Evolutions:
II) Paladin Virtue for frames that can achieve the requirement (Archon Flow and/or Archon shards) is the only one worth, otherwise forced on Hoplite Virtue & Elemental Balance and you either a) drop both crit mods for Scorch & non-primed Expel Corrupted/Grineer or b) drop Gambit for primed Expel (higher dps). In either case, unless you break your shield every 8sec, Hoplite Virtue is like having a worse KNukor (https://overframe.gg/build/491132).

III) Preference. I don't think 2s reload warrants using Resonant Restore's magazine increase, so I'd personally go ammo evolution (Mercenary Chamber) + range exilus or range evolution (Moonrise Velocity) + ammo exilus. 21 pickups with ammo exilus (12 with primed version) are needed to break even with Mercenary Chamber.

IV)
i) With Arcane Avenger active, Elemental Balance & an Expel Corrupted/Grineer over Primed Pistol Gambit yields max dps, but keep in mind Avenger isn't consistent (only lasts 12 sec, realistically 10, while often taking more than 8 kills to proc).
ii) Without Arcane Avenger active, [Atomos] deals ~83% more AoE dps than viral heat KNukor (vs armored Exo Gokstad Officers). This is achieved with
1) Survivor's Edge & the above build or
2) Elemental Balance & Primed Expel (not normal Expel) instead of Primed Pistol Gambit (this version starts doing better vs targets that take 2 or more seconds to die).
The non-SP/Infested config uses Commodore's Fortune (https://overframe.gg/build/491559).

BUILD DETAILS
-Even if GShot doesn't factor the extra base damage from evolution II, its diminished boost combined with its high status chance are enough to outperform competing mods. Don't add more fire rate instead, it'd waste ammo too quickly in lengthy/low enemy density missions.

-Lowering viral ranks to increase heat status weight doesn't increase dps here, as it also lowers total status chance.

-On Infested & non-SP Corrupted/Grineer missions this build kills faster: https://overframe.gg/build/491559.