Your Diablo 4 Ancestral items are the most powerful pieces of gear you can get while slaying elites and delving dungeons across Sanctuary. An Ancestral Unique helmet, for instance, is often far better than a Sacred Unique helmet, though an item's quality always comes down to RNG and whether you get good affix rolls, too.
If you're new to Diablo 4's endgame, your Paragon Board and Glyphs are super important in getting strong and handling the ever-increasing difficulty of Nightmare Dungeons. That said, here's how to get Diablo 4 Ancestral items, plus why they're really good.
How to get Ancestral items
To get Ancestral items, you need to be in the Torment world tier. This means that you have to first reach level 50 and complete the capstone dungeon in Kyovoshad's main cathedral, allowing you to change your world tier to Nightmare. After this, you'll need to complete the Fallen Temple capstone dungeon in the Dry Steppes. This is a level 70 dungeon and is very difficult to complete if you're under level. Still, it's more than possible if you have a party supporting you or a decent build—I finished it at level 60, for instance.
Once complete, head to the world tier statue in Kyovoshad's main square and change it from Nightmare to Torment. This unlocks Ancestral items as a potential world drop. You can get them from chests, events, dungeons, by defeating elites, and you can also potentially get them from the Purveyor of Curiosities with your Murmuring Obols. If you do get into Torment world tier before you reach level 70, it's worth considering that it'll be quite hard to kill elites and complete the events and dungeons you'll need to get these items, since you'll still be under leveled.
What are Ancestral items?
Just like Sacred items, Ancestral gear is an affix that can apply to any of the normal gear rarity levels. For example, you can have an Ancestral Rare amulet, or even an Ancestral Unique amulet. The key difference is that Ancestral items are better than Sacred items, rolling even higher stats and getting higher overall item power.
Ancestral items often roll over the highest item power breakpoint, i.e 725, meaning the stats that they have are the best those stats are going to get, plus a few extra points with item upgrades. This generally makes Ancestral items the best to use when you're creating a build. When sorting through your dungeon haul, you should definitely be checking and holding onto any particularly good Ancestral rolls.
Once you start properly playing on Torment world tier and doing Nightmare Dungeons above tier 20, you'll get a lot of Ancestral items, since they aren't particularly rare. It's also worth noting that you can recognise them easily by the white glow at the top of their item icon.