Delve



A delve is the exploration of the infinite Azurite Mine dungeon, released in the Delve league. The character guides a Crawler (mine cart) powered by Voltaxic Sulphite through the mines to a checkpoint. Players can start delving from act 4 onwards, when they start encountering Niko, Master of the Depths.

Sulphite
Voltaxic Sulphite is used to travel to undiscovered checkpoints in the Azurite Mine. From act 4 onwards, zones can spawn 3 caches of Sulphite. Clicking on it will summon Niko to harvest it. The higher the zone level, the more Sulphite is gained. In maps, the amount of Sulphite received can be increased with map quantity. Nearby party members will also receive the harvested Sulphite. The Sulphite in maps can be increased with certain Scarabs.

Players can only hold up to a certain amount of Sulphite at a time. The maximum Sulphite capacity can be upgraded using Azurite. The amount of Sulphite needed to navigate from one checkpoint to another depends on the depth and the length of the path, up to a maximum of 1100 Sulphite per segment.

Sulphite scaling based on area level
Those are base values and can be further modified by map quantity. In maps, effective area level is used instead of base area level.

Darkness
Light and darkness play an important role, as the player character takes increasingly high damage over time when outside of any lit areas in the form of a stacking debuff. The debuff deals damage equal to 2% of the player's life and energy shield per second, gaining a stack every 0.25 seconds (maximum 5000 stacks). Stepping into a lit area clears the debuff. Allied minions and totems will not take darkness damage. Additionally, monsters within the darkness cannot be damaged.

Light is primarily emitted by the Crawler, cables that are generated in cleared paths, and Flares. Flares are consumable items that can be thrown the create a temporary lit area. Its radius, duration, and maximum capacity can be upgraded with Azurite. Stalkers, a monster found in Delves, can temporarily disable sources of light.

The player's resistance to darkness damage and light radius decreases when delving deeper in the mine. Darkness resistance and light radius can be upgraded with Azurite.

Generic light radius modifiers will not work in the Azurite Mine.

Crawler
The Crawler is used to navigate to undiscovered checkpoints, powered by Sulphite. The Crawler will automatically navigate to the chosen waypoint, providing light around it. If players move ahead of its path, it will greatly speed up to catch up to them and stops if players move too far away from it. The crawlers speed is based on the characters movement speed.

The Crawler will also pick up items dropped within a large radius around it, which it drops when the checkpoint and encounter is cleared.

Dynamite
Dynamite is used to destroy fractured walls, which are hidden in dark areas off the path. Each wall takes only one dynamite to destroy. Dynamite can also be used to deal damage to enemies.

Dynamite capacity, radius, and damage can be upgraded with Azurite.

Azurite Mine
The mine can be explored going downwards (increasing the difficulty) and laterally.

Progress is the mine is shared between all characters in a league; different leagues will have different layouts of the mine. When playing in parties, the process is tied to the owner of the mine and other party members cannot continue if the owner leaves.

In each delve, players navigate from one checkpoint to another undiscovered one. At the end of the checkpoint, there will usually be an encounter of some kind. Once the encounter is cleared, the Crawler will drop all the items it picked up and any loot containers nearby can be opened. Each checkpoint drops different rewards, indicated by its icon.

Grids can contain zone modifiers, increasing in difficulty. The lower the depth, the more likely a grid will have a zone modifier.

Instance
When loading into a delve checkpoint, the game will spawn an instance with all possible areas in a 5x5 grid around it. If players take a path that goes outside the instance's 5x5 grid or load a path that requires relocating the Crawler, a new instance is created. When moving from a checkpoint where the Crawler is to a nearby checkpoint, the Crawler will move there without loading a new instance. Players dying in the instance will not be able to return to it.

When in a group, a portal to the instance will spawn when the party leader creates a delve instance. If the party leader dies inside the instance, a portal will spawn.

To return to the current instance from the Mine Encampment, click the icon in the top left corner of the Subterranean Chart marked "Visit: The Mine" to teleport to the last checkpoint used.

Hidden loot
The mines contain many small containers of loot, often hidden away in the darkness. These containers do not display its item name unless players are close enough to it and have a faint sparkle around it. They are often found in side paths where the Crawler passes by.

They can contain items, fossils, resonators, flares, dynamites, or Azurite.

Fractured walls
Fractured walls can be found hidden in dark areas. They will be marked on the minimap if you are close enough and and hovering over it will show the wall's health bar. These walls can be destroyed with a dynamite. Behind fractured walls are rare loot containers and sometimes, a hidden path to an inaccessible checkpoint.

There will always be at least one fractured wall in grids that do not contain checkpoints.

Hidden path
Some checkpoints have no paths leading into it. This means it is hidden behind a fractured wall. Once the wall is destroyed, players can send the Crawler to that checkpoint.

To find the hidden wall more easily, note the path creation rule:
 * A checkpoint will generally only have 1, 3, or 4 paths leading out of it. 2-way nodes are rare, but are possible when the generator tries to create a path that is too long.
 * A fractured wall spawns in an empty square, so nodes directly next to a hidden node are not valid options.
 * It's not possible to create more than one path in a cardinal direction.
 * It's not possible to overlap an existing path.

If a checkpoint has 2 paths, it is likely that there is a hidden path near it. If there are no checkpoints with 2 paths, check the checkpoints with 3 paths. It is also possible for a checkpoint with a single path (which is usually a dead-end) to contain 2 hidden paths out of it. Rarely, an overly long path to a hidden node can be generated and result in a dead end node having a single hidden wall and creating a 2-way node.

Betrayal Changes

 * It is possible for a checkpoint to have only 2 paths, if 1 path connects 2 checkpoints further than 5 tiles apart.

Mineshaft
As a character levels up, Niko will dig a mineshaft that goes straight down from the Mine Encampment. Mineshaft length is shared among all characters in the league, and is based on the highest level character of that league. Niko will stop digging mineshafts at depth 34 (monster level 68).

The mineshaft is intended as a catch-up mechanic for players that don't progress delves during the campaign. The mineshaft is a straight downward path with nothing inside. It will override any node it spawns over.

Biomes
The Azurite Mine contains six common biomes, each with different monsters, encounters, and common fossil drops. Rarely, a city biome will spawn, which contains better loot and rarely, a special boss, but are more difficult and denser.

Weights
Current theory on weights:

The weight is scaled between the lower and upper entries based on current delve depth. See the table below for data mined values.

If your character is below or at depth 50, the biome will not spawn.

If your character is between 50 and 100, the biome will spawn and the weight will increase accordingly;
 * Depth 51, 2 weight
 * Depth 52, 4 weight
 * Depth 99, 98 weight
 * Depth 100, 100 weight
 * Depth 100, 100 weight

If your character is below depth 100, the biome will always have a weight of 100

Bosses
A city biome may contain a special boss. Each boss can only spawn below a certain minimum depth.

Minor bosses
There are other minor unique bosses for other Delve nodes, such as:

Nodes
Biome Specific Nodes:

Common Nodes:

Sulphite cost caps at 1100 at depth 890 and beyond.

There is additional scaling starting at depth 1600, which caps out at around depth 2586.

Spending Azurite
Azurite can be spent with Niko to purchase resonators. It can also be spent at the Generator to purchase flares and dynamite or upgrade their effectiveness or capacity. You can also upgrade delve attributes, such as Sulphite Capacity, Darkness Resistance, and Light Radius. The costs for these upgrades scale upwards quickly as shown in the tables below, however early upgrades can become discounted from the listed values if you delve deeper.

Version history

 * Maps dropped by special sources such as deterministic chests or league rewards like those found in the Azurite Mine or the Temple of Atzoatl now use your own Atlas to determine which maps to drop, and can therefore drop maps that have been raised above their base tier due to the presence of Watchstones. Maps dropped from these sources now also take into account your Favourite Map selections. If a source such as this cannot find a compatible map from your Atlas to drop (for example, due to too few maps being completed and too few watchstones being socketed for a Tier 16 map on your Atlas to drop), it will drop a random map of the correct tier instead.


 * The Azurite Mine is now capped at Depth Level 65,535.


 * Your Voltaxic Sulphite is now shared across all characters on the same account and in the same league. There is still a hard upper limit of 65000 Sulphite. Characters that are merged to Standard at the end of a league will bring their Sulphite with them, up to whatever your highest maximum Sulphite limit is.
 * The tunnel Niko digs for you based on your character level is now also shared league-wide across all your characters, meaning your highest-level character will determine the depth of Niko's tunnel for all characters. This tunnel will only ever, at most, be 6 levels behind your highest-level character until you reach level 68. Previously, it was 15 levels behind by the time you reach level 68.
 * The rate of level growth for monsters within the Azurite Mine is now faster, requiring significantly fewer depths to hit the maximum monster levels within the Mine. This was because most players progressed through the Atlas faster than the Mine, and the two difficulty levels would quickly become out of sync.
 * As a result of the change to the depth-to-level ratio, the cost of Delves in those interim levels has been increased, but tapers back to the original costs as you get deeper.
 * You can now find Legion encounters and rewards in the Azurite Mine.


 * Introduced to the game in the Delve leagues.
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