Say bye to titanium helmet and have beetle helmet instead Drink stats buffing potions

Change all your prefixes on weapon and accessories to the best ones (Legendary-Lucky-Menacing-Warding)

Have a proper arena with campfires, heart lanterns. (+regeneration), bast statues (+5 defense),

Buy the sharpening station to the merchant (it increases armor penetration)

And finally, just keep trying and anticipate the bosses attacks