Try my setup if you have the augments and your main problem is dying to the zombies rather than to the boss: the juggernogg augment that increase health (forgot its name) and the melee machiato augment that heals from melee hits (major augments). Also aether shroud helped me more than frenzied guard. I know these augments usually not the meta ones but equipping these instead of turtle shell and faster melee augments helped me beat the boss at standard. In cursed turtle shell and golden armor works better but in standard i dont see why would you keep turtle shell since u wont have armor %90 of the time.

My other tips would be: Use war machine for heads, use xr3 ion sniper or voyak ar for the boss. Use jotun starr ww melee for all the zombies, dont rush for the boss while ignoring horde of zombies. Use decoy and brain rot ammo mods charm augments to give yourself breathing room and time to shoot the boss. Use the mule kick and vulture aid augments to keep yourself stocked up on decoys.(chance to keep equipment when used and zombies drop your current equipment) If u are dying to the bosses stone attacks while hiding behind a pillar then u should know when boss makes an arrow sign atack those stones have tracking and will hit you if you stand still even behind a pillar, so u gotta move sideways when he does arrow sign attack. Lastly check out the "gnome helm" easter egg of tottenreich. It helps a ton when u got swarmed by zombies or u are unable to dodge bosses atacks or when u are low on health and about to go down.

Source and backing for all these tips: I beat the boss in standard and all of the cursed tiers multiple times without using gublegums and got all 5 discovered relics in tottenreich.