[Lavos] can be a good focus farmer in ESO. I've compared the damage output of every focus farmer and only Volt Prime overpowers Lavos.

Tips:

-If you are going to do solo runs, use your elements depending on the factions. If you are in a team that has another dps, mostly use viral, corrosive or magnetic depending on the faction to let your dps deal huge damage and kill everything faster.

-Most of the ESO tilesets have 2 or 3 floors. Try to cast your 4 (Catalyze) on the middle of the tileset as much as possible because Catalyze can hit enemies just above or below it.

-[Lavos] doesn't have energy but has cooldowns and those cooldowns can be removed with his 3rd skill. Even though overframe shows that the 3rd skill removes 1.3 seconds of cooldowns per enemy hit, in game it is actually 1.95 seconds. This also applies to cooldowns put on your skills by Simaris. If only DE gave us Lavos' 3rd on helminth...

-Don't use your 1st skill too much as it doesn't do anything but proc some stats and steal hp. When you get to zone 5+ you might get under heavy fire and die because we don't have any survivability in this build. You can only rely on your 1st so having it ready all the time is key.

-Natural Talent is optional. You can switch it with more Ability Duration or Strength. I just like to cast my 4 faster tbh.

-Since [Lavos] doesn't have energy, Ability Efficiency is not used to reduce energy cost. Increasing your Efficiency lets you have more cooldown reduction per enemy hit with your 3rd.

-When playing [Lavos], there will be another stat called Status Duration which has the same amount of your Ability Duration. Status Duration indicates the amount of time that your status procs either by your skills or by your weapons on enemies. You don't need to get more than 100% status duration since you will be proc'ing stats often so try not to reduce it too much.

-For the last, you can use any aura except [Energy Siphon]. If you want to save another forma you can use [Corrosive Projection]. I use aura formas on every warframe that I own so I can have flexible builds.