The Nyctocosm is a datapack that expands the Deep Dark by allowing the Ancient City portal to be activated, leading to a new dimension with custom biomes, weapons, and bosses. A new feature added in this datapack is the ability to cast spells, which require various ingredients and perform different tasks.

The Nyctopedia is a great reference for the datapack's features, but this page will condense the concept of spells into a single article. The article may also serve as a quick-start guide for new players looking to start their journey into the datapack.

The Seelic Scythe is the figurative gateway into the Nyctocosm world. Crafting it requires the player to enter an Ancient City found in the Deep Dark, which is commonly located under snowy mountains. Its recipe requires 3 Echo Shards (found occasionally in Ancient City chests) and 2 Sticks as shown:

Like all weapons in the datapack, the Seelic Scythe cannot be enchanted, but is unbreakable and comes with special abilities. One of them is a right-click ability that instantly teleports the player 6 blocks forward and damages entities in its trail. However, this deals some damage to the player as well.

The scythe also harvests the soul of any mob it kills, which lingers for a few seconds and can be collected by standing close to the soul particles with an empty bottle to obtain a Soul Bottle, which is stackable. This item is used in one method of casting spells, and for activating the Dias of Incultation for the second.

This second method requires a bit more resources (primarily a Beacon or Nether Star from a Wither) but is more useful overall. The Planar Coil also stores souls when held in the offhand slot and is acquired with 20 Seelic Essence (which costs 20 Soul Sand and 5 Blaze Rods) and 4 Golden Ingots.

These materials can be traded in the Dias of Incultation (which is really just an invisible custom villager). Building it requires 4 Quartz Blocks, 4 Quartz Stairs, 4 Waxed Cut Copper Slabs, 1 Beacon, 1 Anvil, and a Lit Candle Ring as seen below. To activate the Dias of Incultation, right-click just above the anvil with a Soul Bottle.

After obtaining the Planar Coil, hold it in the offhand to accumulate souls harvested from the Seelic Scythe. There is no limit to the amount of souls that can be collected.

Spells require two ingredients: A Spell Plane and the core spell material. The first method of casting spells requires 25 lit candles arranged in a 7x7 circle like so:

The player must right-click a Soul Bottle while inside the circle for the Spell Plane to appear. Note: the soul will be consumed on use, and the Spell Plane will disappear if the player leaves the circle.

The second spellcasting method involves the Planar Coil. Holding it in the offhand and right-clicking with an empty hand while sneaking consumes a soul and creates a Spell Plane at the player's feet. Once again, leaving the circle will cause the plane to disappear.

To cast a spell, simply drop the corresponding material while in the Spell Plane. The most important spells are Resonance (Echo Shard), which activates the Ancient City portal when aimed at it, Luminescence (Glowstone), which grants immunity to the Blindness effect applied when in the Nyctocosm in low light levels, and Evanescence (Eye of Ender), which allows the player to teleport to their spawn point and escape the dimension.

A complete list of spells, their materials, and their effects are shown in the table below.

Note: These numbers come from the wiki and have not been tested. Some, like duration, may not be accurate in-game (actual times are ~10% of the displayed time in seconds).

After entering the portal and exploring the various biomes of the Nyctocosm, a "Stonehenge-like structure" might be visible above ground in the Night Wastes.

Digging underground near the monument will lead to the Crypt, a stronghold-like structure made of stone bricks.

When entering the structure, say hi to Tony, the invulnerable cat who will appear and leave behind a lore book of its own. The Crypt consists of many rooms connected by winding tunnels, but chests with valuable loot can be found here. While the loot is very similar to Ancient City chests, with Enchanted Golden Apples, diamond leggings, and Swift Sneak, each box has a random custom artifact, with the "dream center" chest containing 3 guaranteed, powerful artifacts: The Dream Scroll of Protection, the Feather of Levitation, and the Tablet of Transposition. Most rely on a system explained in the next section.

Hypertraces make up a mysterious system stemming from a side effect of using spells. When dealing magic damage or casting a spell, the player has a 15% chance to create a Hypertrace, an orange floating halo that lingers for a few seconds before disappearing.

To pick up a Hypertrace, right-click the halo or sneak + right-click to pick up all created Hypertraces. This adds to the player's "Hypertrace Charge", which cannot be seen but is used by some artifacts and has a maximum of 15 (starts at 5, but the method of upgrading this number is unknown).

Standing close to (within 6 blocks) or destroying Hypertraces (left-click, or sneak + left-click for all) also activates some artifacts' abilities. More information is shown in the next section.

Found in Crypt chests, these custom utility items empower spellcasting or grant special effects. A complete list of Artifacts and their conditions is shown below.