[Lavos] has good survivability in his base stats along with the healing from Ophidian [Bite]. This build attempts to make him into a tank while still having decent stat spread to use his abilities. We don't subsume an ability in the recommended build as it takes away several of your element choices. Use the Helminth abilities with great caution.
Quiver is a decent options to stall out enemies while you heal yourself. Dispensary allows you to abuse mods like [Health Conversion] and [Energy Conversion]. Other choices work but are losses of synergy that you should take with caution.
Replacing an ability isn't easy on [Lavos]. Even his more questionable abilities like Ophidian [Bite] and Vial [Rush] grant you Toxin and Cold to your abilities respectively. Catalyze has a very long cooldown and is fairly weak on most enemies without significant stat/status investment, but you lose out on Heat.
Survivability is first and foremost in this build. We will do a small mod swap breakdown on a few mods but always remember that all builds of this nature fall apart in level cap endurance as no amount of defense will [Protect] you from millions of DPS.
[Aerodynamic] and [Aviator] grant you massive damage reduction by simply jumping in the air. Aerial combat isn't difficult with guns but if you're trying to use a melee build these both should be swapped out at your discretion.
[Health Conversion] and [Energy Conversion] both proc off of Universal Orbs made by Transmutation Probes. This build isn't really attempting to abuse combos so your shouldn't be forced to use the probes on anything other than orbs for additional survivability.
Efficiency is useless on [Lavos]. Even though it increases the amount of cooldown reduction you receive from Transmutation Probe, it does nothing to the probe itself so you're still forced to wait 10 seconds after every rotation no matter how good it is. You can swap out [Blind Rage] but your Range is high enough that it shouldn't be necessary.
[Natural Talent] is extremely important. [Lavos] has to do heavy ability spam in order to set up his following abilities.
[Rolling Guard] can be swapped in over [Adaptation] if you're facing enemies that do singular powerful attacks rather than many small ones.
Arcane Aegis grants you great survivability when it procs but can be replaced if you don't like the RNG. Arcane [Guardian] doubles down on survivability as you're going to be rooted while casting some abilities. Replace either to suit your playstyle.