Don't use this build if you're advanced enough to pick up Galvanized mods. These builds are better for that:

THeMooN85: https://overframe.gg/build/798/ignis-wraith/pestilence-carrier/

GKP_light: https://overframe.gg/build/20820/ignis-wraith/viral-ignis-wraith-most-effective-build-without-riven-305/

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Exilus Mod slot is ignored because there's nothing that can go in that slot that's needed in my mind, but it's mostly personal preference. You could slot in [Vigilante Supplies] for ammo + crit boost if you want to spend another forma, but this weapon already has a ton of ammo and crits constantly so it's not needed in my opinion.

More DPS could likely be squeezed out by using some of the "while aiming" mods, but I didn't want to mess with that. Just give me pure damage no matter if I'm flying, sliding, aiming, or just holding my left mouse button. I also don't care about switching out mods or configs all the time depending on the enemies I'm facing unless I'm farming Index (Corpus) or Endo on Vodyanoi (Grineer). So if you're lazy and don't have a riven, or you're going up against sub level 100 enemies and they all melt in a matter of seconds anyway, this is about as good as it gets.

It's technically A LOT better to use Faction Damage mods (Bane, Smite, Expel, etc) because of the way similar mods have diminishing returns.

Example:
[Serration] (+165% damage) plus [Heavy Caliber] (+165% damage) is NOT 165+165=330% damage

This build's +damage from the Primary Merciless arcane and [Serration] is also diminished, which is why usually weapon builds only have the arcane and zero +damage mods. But in this case, I'm lazy. Again, this build is NOT the best way to do things - it's just a quick setup for melting sub level 100 content.

More info on diminishing returns here