The 
Soul Crystal is a rare crafting material from the Deeper and Darker mod, and the only creature that drops it is the Stalker, which crawls out of fake Ancient Vases in Ancient Cities and Ancient Temples. You’ll need at least three of them for the mod’s two best items, the 
Soul Elytra and the 
Sonorous Staff.
They’re also used to repair both of those items, and to brew a Potion of Sculk Affinity, which stops your movement from setting off Sculk Sensors. Since every Soul Crystal means finding and beating a Stalker, it’s worth knowing how the vases work before you start breaking them.
Obtaining
Every Stalker drops one Soul Crystal when it’s killed, and Looting adds up to one more for each level, so a Looting III weapon can get you as many as four from a single kill. There’s no recipe for Soul Crystals, which means the Stalker is the only reliable way to get them.
Stalkers don’t spawn on their own in any biome. Instead, when you break an 
Ancient Vase there’s a chance it was a fake, and a fake vase will release either 1 to 3 Sculk Leeches or a Stalker. With the default config, 16% of vases are fake and 31.25% of those hold a Stalker, which works out at about one Stalker for every 20 vases.
| Source | Amount | Chance |
|---|---|---|
| Stalker | 1 (+1 per Looting level) | Always |
| Ancient Temple fountain Chest | 1 to 2 | About 2% per Chest |
The vases that can be fake are the ones that generate in the walls of Ancient Cities and all through the Ancient Temple, so you’re able to start farming before you’ve even been to the Otherside. Any vase you’ve placed yourself is always safe, and fake vases won’t do anything on Peaceful or with mob spawning turned off.
Ancient Temple Chests
The Chests around the fountain in an Ancient Temple can also hold 1 or 2 Soul Crystals, though it’s one of the rarest things in that loot table. It’s a nice bonus if you find one, but you’ll get far more by breaking every vase in the temple on the way through.
Uses
Most players are after Soul Crystals for the Soul Elytra, which takes one along with an 
Elytra, four 
Sculk Bones and two 
Soul Dust. The Sonorous Staff needs two more, together with two Sculk Bones and the 
Heart of the Deep from the Warden.
Both of these are repaired with Soul Crystals at an 
Anvil, which is why it’s worth keeping a few spare after you’ve crafted them. Mending works on both as well, and it’ll save you a lot of Stalker hunting over time.
Brewing
Adding a Soul Crystal to an Awkward Potion in a 
Brewing Stand will give you a Potion of Sculk Affinity, which lasts for 3 minutes. Adding 
Redstone Dust afterward stretches that out to 8 minutes, and there’s more on what the effect does on the Sculk Affinity and Sculk Omen page.
You’re also able to brew the same potion from a Potion of Invisibility and a single Soul Dust, which is a lot easier to come by. It’s worth doing it that way and keeping your Soul Crystals for gear.
Farming Soul Crystals
The quickest way to farm them is to raise the chance of fake vases with Sculk Omen. If you drink an 
Ominous Bottle and then walk into an Ancient Temple, your Bad Omen turns into Sculk Omen of the same level, and it lasts for 15 minutes.
| Effect | Fake Vase | Stalker |
|---|---|---|
| None | 16% | 5% |
| Sculk Omen I | 17.4% | 5.4% |
| Sculk Omen III | 43.7% | 13.7% |
| Sculk Omen V | 68.1% | 21.3% |
At Sculk Omen V, roughly one vase in five will have a Stalker inside, so a single temple can give you several Soul Crystals in one visit. Bring a weapon with Looting III and Sculk Smite, as the Stalker has 200 health and hits very hard, and the Leeches from the other fake vases will be crawling around as well.
FAQ
Soul Crystals drop from the Stalker, which only appears when you break a fake Ancient Vase in an Ancient City or Ancient Temple. Each Stalker drops one, plus up to one more per level of Looting, and the fountain Chests in Ancient Temples have a small chance to hold 1 or 2 as well.
They’re used to craft the Soul Elytra, which takes one, and the Sonorous Staff, which takes two. They also repair both of those at an Anvil, and adding one to an Awkward Potion will brew a Potion of Sculk Affinity.
Soul Crystals can’t be crafted, as there’s no recipe for them in the mod. You’ll have to get them from Stalkers or from Ancient Temple Chests, so the vases in Ancient Cities and Ancient Temples are where most of yours will come from.
Having Sculk Omen makes vases far more likely to be fake, and you’ll get it by walking into an Ancient Temple with Bad Omen from an Ominous Bottle. At level V, about 21% of the vases you break will release a Stalker, compared to 5% normally.
