Mixing and matching gear lies at the heart of Diablo 4's buildcrafting. Players can get some insanely powerful combos going once they get the right effects in place, but this system does come with some noteworthy limitations.
The Diablo 4 experience might be a power fantasy, but having things that are too brokenly strong is still bad for the game's health. With that said, some things just aren't possible, even with the myriad of Legendary Aspects that players can get as they play.
Do Legendary Aspects Stack In Diablo 4?
The short answer is no, they don't. Players cannot use more than one copy of the same Aspect in their builds. Doing so will gray out the Aspect description on one of the redundant Legendary Items, indicating that it is not providing any benefits to the player.
However, different Aspects under the same category (Offensive, Defensive, Utility, or Resource) do synergize with each other. This means players can gain multiple effects that buff their damage or survivability, greatly increasing the power of their characters. Aspects that have related or overlapping effects, such as Edgemaster's Aspect and the Barbarian-specific Aspect of Limitless Rage, will work together—the important part is that players do not have two of the same Aspect equipped.
It's worth mentioning that two of the same Unique item cannot be equipped either. Not only does this prevent the double-dipping of Unique powers, but it also keeps players from enjoying two sets of the same affixes provided by Unique items.
What To Do With Duplicate Legendary Items
As players continue their adventures throughout Sanctuary, they'll eventually get items that have the same Aspects as the ones they already have equipped. Do not throw these away, as the stats of these legendary powers differ from item to item. One 2H Sword with the Edgemaster's Aspect may have a 30% damage bonus while another might come with a max 40% roll.
In case this happens, players should take the duplicate to the nearest Occultist and extract the Aspect for future use. The power will be stored in a dedicated inventory tab. Extracted Aspects can also be stored in the Stash.
If a duplicate item rolls with an inferior version of an Aspect, then players should take it to the Blacksmith instead for salvaging. This is one of the ways to obtain Coiling Wards, Abstruse Sigils, and Baleful Fragments, all of which are used to upgrade legendary gear or imprint Aspects onto rare gear.
Unique affixes cannot be salvaged, which sort of complicates things. There will be times when a Unique will drop with a stronger Unique power but with weaker stat affix rolls. In this case, players will just have to gauge which of the two is more important and bite the bullet. Uniques can still be salvaged, though.
Diablo 4 is available now on PC, PS4, PS5, Xbox One, and Xbox Series X/S.