I’m somewhat new to the game, have been playing for a while but just now have gotten into the “end game” of D3. I understand that builds are cohesive and so you can have pieces that match each other. But I don’t understand why I would use all these pieces for my build if it lowers my dmg by hundreds of thousands and my other stats. I have been trying to build the popular Crusader Aegis of Valor Heaven’s Fury Build. I have most of the pieces but a lot of them lower my stats even though they are lvl 70 pieces. Should I reroll in the cube so they might get better? Plz help this noob out
First thing to do is look at the Roland’s Legacy set you have on. It buffs Shield Bash and Sweep Attack - neither of those are one of your chosen skills. Go through and make sure your gear buffs match your chosen skills. If needing changed, visit the mystic. Do that every time you find new gear. That’s a common error among new players, they see the +green numbers when comparing items and don’t factor in the associated buffs and bonuses.
Also, get a different weapon. Your Warmonger has +intellect on it. Int. is the last stat Crusaders need. You want strength.
Also, note, that what shows as the damage you do on the character screen (the “sheet”) does not necessarily reflect what you actually inflict. For example, my monk shows 1.4m damage on the screen but everything I hit takes billions, usually 100s of billions (I’m not up there to get the trillions yet, but I know it is possible.)
Even when an item says it improves your attack (the 
symbol), it may actually make you do less based on other factors as mentioned upstream.
One thing to check is maxroll.gg as they have “mechanics” sections for each of the suggested builds to better explain why and how to use it. Once you’ve gotten the fundamentals, break out into something you enjoy.