Thanks for suggestions, DEX looks more profitable than PER but my shots missed pretty much every time so I picked more PER, also I didn't want to use any psi in this run.
When I was making that build I had Caustic from Apex in mind, dude that can gas entire room while laughing in agonizing enemy's face.
Pretty much every encounter I won just by shooting my Acid gun against non mutant and non bug enemies, and freeze gun against bugs.
But in harder fights I just lay traps in circle formation or in corridor and toss gas grenade inside or behind them. If enemies still alive and trying to disarm my death fog machines, I'll just freeze or entangle them from stealth. This strategy works perfectly in open and closed space, it even outright annihilates deathstalkers. And even if you corenered or don't have space for maneuvers you can just toss gas grenade under your legs or where enemies can't see them and lure them there without any problems cause Chemical Assault Armor or insulated armor.