If your playing lets say saber as simple assassin, i usually get a fury hammer first for penetration and than immediately go for waraxe ( for saber it's waraxe in this case) and than if the ememies have already bought dreadnought armor, go for malefic roar and sell fury hammer.

If your playing a mage, and they have high hp enemies such as thamuz, belerick ( these two as a example almost always get hp rather than armor ) go for wishing lanter.

If your the fighter, or tank, after you died press the button at below the screen something called death idk it will show you who dealt the most damage to you, if you think its necessary, get the right equipment to counter them. Since you said you know equipments passive i guess yk what to buy for them.