I'll be repeating myself on some parts from [Fun Experiment 5] Gas Status plans. - General Discussion - Warframe Forums but I'll quickly go over Lavos specifically.
With Status duration being raised from his Ability Duration, Lavos can reach 18.36 seconds just from ability duration and add some more from weapon +Status Duration mods.
All weapons can have decent +Status Duration but primary and melee can get +100% Status Duration in one mod.
Using primary or melee and +306% Ability duration we now reach 24.36 seconds for our status.
It's quite easy to stack Gas on an enemy but we don't want any Gas Clouds, we want Gas Clouds that deal the highest damage possible so we'll have to use either a powerful primary or a powerful melee weapon.
We have much more choice on the melee side because of how the melee system is, with combo and heavy attacks, it is fairly easy to reach high damage.
Unfortunately there's no strong Gas Weapon, so we'll have to mod our weapon to proc Gas consistently, so that we get Gas Clouds on almost every hit.
Alot of melee weapons have high damage and decent status to allow Gas to proc often but not consistently. Infusing Nourish on Lavos through the helminth can greatly help to pull up the Gas damage ratio as to proc it consistently.
From there we can either, melee with normal attacks and combo to get more Status chance through Weeping Wounds, spawning Gas Clouds wherever we go.
Or. We can use heavy attack builds for a high burst of damage on each Gas Clouds. We might spawn less often because heavy attacks are most of the time slower than regular attacks but the damage is nothing to laugh at.
When talking heavy attacks we could use the same weapons as the previous way or we could use weapons with specific mechanics around heavy attacks. Like Glaives or some bonker weapon like Vitrica.
For most weapons we'll have to look closely at status chance but not with Vitrica, the glass shattering has 100% Status Chance unaffected by mods. So not only we already have what we wanted but adding more wouldn't do anything at all.
The only concern is the damage ratio but we already covered that with our build and Nourish infused.
Make sure to add a +100% Status duration mod to get that extra +6 Seconds, with a riven you could get even more.
No matter the build you chose, all your Gas Clouds are now landmines for enemies to step in. And if the damage is high enough, death traps.
In this scenario I have a preference for range attacks even if I use melee weapons, and spawning gas clouds in doorways or corridors is always a better trade.
There are multiple hidden mechanics allowing Gas Clouds to synergize with some weapons and arcanes, curious players might be able find these few exceptions making this tactic even more effective.
Happy Hunting, Tenno 😁