Niko & the Azurite Mine
Niko the Mad
Once you've opened up the mine early in Act 4's main story, you'll meet Niko the Mad (who is standing right by the entrance). Niko is another recurring NPC associated with a major side mechanic, similar to Einhar from back in Act 2.
Niko is interested in exploring the Mines into their very deepest depths. The Eternals weren't the first civilization to pursue the Beast's powers, and every major civilization of Wraeclast's past has left their mark deep in its depths. There's great treasure to be found in the Mines, although the shadows in the depths do seem weirdly alive...
The Azurite Mine
While questing through the world or playing through the endgame Map system, you'll occasionally encounter Niko in a zone. When he appears, it'll be along with several deposits of Voltaxic Sulphite, which will be scattered around the map Niko is in. These deposits are essentially a "fuel" that allows you to access the Azurite Mine (more on this below). Clicking on a deposit collects it, and displays a small indicator at the top-right of your screen showing how much room you have for more Sulphite before you need to use some (not shown in the image below).
The Azurite Mine is an infinite series of dungeons in which you descend into a dark mine following a 'Crawler' that illuminates the darkness. Leaving the Crawler's light causes you to take rapidly increasing (and soon fatal) damage, but there are chests to be found along the Crawler's path just outside of the light. Your goal is to keep up with the Crawler, fend off waves of attacking monsters, grab what loot you can, and keep up with the light as it travels (lest you be left behind in the hungering darkness).
The Azurite Mine is infinite and procedurally generated both horizontally and vertically. The deeper you descend into the depths, the more difficult the monsters and the greater your rewards.
Once you've gained access to the Mine, you can use your Sulphite to power expeditions ("Delves") into the dark. To do so, head to the Mine Encampment from any Waypoint (it's the small icon with a candle at the bottom-right). While at the Crawler or in the Encampment's central camp, you can click any icon on the map that is connected to areas you've already explored to begin a Delve towards that location.
Once you begin a Delve, the Crawler will begin to move at a moderate pace through the dark. Monsters based in the darkness will begin to attack you, and are vulnerable only within the Crawler's light radius. These monsters are fairly dangerous, often more so than the monsters you're fighting during your normal adventures, and you need to fend them off while keeping up with the Crawler. Monsters outside of the light are immune to damage.
If you die during the Delve, your progress is reset back to the start of that Delve, and you lose any Sulphite consumed by the Crawler during that Delve (you do, however, keep any items you've looted, and it doesn't affect your previous progress in the Mine). You won't be able to return to the instance of the Delve you were in, so any items that had dropped (but that you hadn't looted yet) will be gone, too.
Once you reach the end of each Delve path, you'll be rewarded (depending on the area) with equipment, Currency, Skill Gems, Azurite (see below for more on Azurite) or other rewards.
Flares & Dynamite
To assist you in hunting for treasure off of the main path, you have two tools available to you: Flares and Dynamite. Each is thrown via a special hotkey (by default, '6' and '7', but you can change this via the 'Input' options menu). They'll show up above your main action bar when you're in the Azurite Mine.
Flares create a small area of light that lasts a short period of time. This light acts the same as the light from the Crawler, making you safe from the darkness' damage and making nearby monsters vulnerable to damage. Flares take a moment to light up, so make sure not to wait until the very last second to throw one!
Dynamite allows you to blast through Fractured Walls found deep in the darkness off of the main path. Blowing open a wall can reveal secret side rooms with special loot. Once the wall is blown open, you can return to the Crawler to travel to them.
Both Flares and Dynamite are purchased and upgraded by spending Azurite (see below).
Azurite is a mineral you can collect in Delves that will allow you to apply permanent upgrades for your Delving. It's found in deposits throughout the Azurite Mine as one of the more common room types, and can be collected simply by touching it (no need to click).
In addition to purchasing and upgrading Flares and Dynamite, you can purchase:
- Increases to your Sulphite capacity, allowing you to collect more without wasting it while in the open world.
- Darkness Resistance, which reduces the damage dealt to you in the darkness of the mine.
- Light Radius, which makes the Crawler brighter (and thus allows you to explore a little bit more without leaving the light).
Fossils & Resonators
In addition to more normal weapon, armor, and currency rewards, the Azurite Mine offers powerful crafting options using Fossils available from Delves. Fossils allow you to influence the crafting of an item by skewing the distribution of its modifiers. For example, one Fossil reads "More Chaos Modifiers, No Lightning Modifiers".
Fossils are used by socketing them in to Resonator items, available at moderate Azurite cost from Niko. Once all the sockets in a Resonator are filled, it can be used like a currency item to modify equipment, and carries the effects of all the different Fossils socketed into it.
Since this sort of crafting is relatively difficult, and since Fossils are fairly valuable, I would recommend that new players simply save their Fossils and sell them later on. But that is, of course, up to you.
Should I do Delves while leveling?
Probably not. At most, try to seek out Azurite near the main path. The reason for this is that Niko will dig to deeper (and more rewarding) depths for you as you level, right up until you finish the main storyline. That said, it won't hurt you to try Delving sometimes.
Why did my Crawler's light vanish?
Some monsters in the mine use an 'EMP' skill that temporarily disables the Crawler's light. Better upgrade that Darkness Resistance!
How do I get to this hidden side room?
You'll need to find a wall in the darkness off of the main path. Delve nodes almost always have 1, 3, or 4 neighbors, so a node with 2 neighbors almost always has a hidden wall nearby.