I love Path of Exile's dungeons. I love them so much I never want to leave them, and when Path of Exile's next expansion launches on August 31, I won't have to. Grinding Gear Games lead designer Chris Wilson tells me an infinite dungeon is something that players have been wanting for awhile. It's easy to see why, considering Path of Exile's endless lure to keep playing hinges on not knowing what epic piece of loot might be around the next corner. But like all things in Path of Exile, Delve, the new expansion, isn't as simple as it sounds.

The story here is one we've all heard before: A maleficent darkness infests an ancient mine brimming with treasure, driving everyone away. Only here, the darkness is literal—Delve is an expansion about exploring a neverending network of caves while constantly fighting to stay safely in the light. Step into the darkness for even a second and you'll start taking obscene amounts of damage, which might be worth it since that's where all the best treasure is.

What's mine is mine

But unlike some previous expansions, which sometimes feel too optional, Delve is significant and enticing.

Like every expansion to Path of Exile, Delve is a temporary challenge league that remixes the core story mode by adding entirely new features to contend with—in this case an endless dungeon. When Delve launches on August 31, players will start brand new characters and race through the league for several months, until the next expansion releases and those characters are retired to Path of Exile's permanent standard story mode.

But unlike some previous expansions, which sometimes feel too optional, Delve is significant and enticing. While it won't entirely supplant Path of Exile's core story and endgame, I can see myself diving into it at every opportunity. Wilson says the first experience players have with the infinite dungeon will happen within ten minutes of making a new character.

I don't know, Niko doesn't look that mad to me?

Delve introduces a new NPC called Niko the Mad, an engineer and inventor who is obsessed with exploring this long-abandoned Azurite mine now plunged into deathly darkness. He's invented a light-emitting vehicle, called a Crawler, that automatically charts a course through the mines and lays a string of lights to illuminate its path. All the player needs to do is follow it to its destination to unlock the next portion of the infinite dungeon.

To power it, though, players need to find a resource out in the world called Voltaxic Sulphite. This is how Delve plugs into the regular progression loop of Path of Exile. While adventuring through the story or endgame, you'll encounter veins of Voltaxic Sulphite and can summon Niko to come and harvest it. Just one vein is enough to do a quick trip through the mines or you can hoard it (to a point) and spend it on a much longer spelunking session. There's no benefit to short or long trips through the mines, Wilson says. It's just giving players the freedom to play Delve how they want.

Once you decide to take a trip into the mines, it's similar to most of Path of Exile's dungeons, only the map is more linear. The Crawler will begin working its way to the end, slowing or speeding up to keep pace with the player while hordes of monsters attack. Stick to the light from the Crawler and you'll be relatively safe—but where's the fun in that?

As the Crawler moves through the dungeon, players will spy all sorts of treasures waiting in the darkness. You can risk trying to grab them for extra sweet loot, but each second spent away from the light will rapidly drain your health. What's worse, monsters will try to ambush you and keep you from making it back to the Crawler in time. It's a tense game of risk versus reward at every step, especially if you're like me and hate the idea of leaving treasure behind.

The darkness is not your ally in Delve.

Fortunately, the Crawler leaves behind a string of lights as it goes. Once it reaches the end of the map, those lights illuminate. After you survive one final fight against a boss or waves of enemies, the delve is complete and you're free to go back and risk diving into darkened areas you skipped.

Even if you're risk-averse and stick to the light, delves will still offer great rewards and nail-biting challenges. Grinding Gear Games has added several new monsters with abilities that screw with the Crawler. One example I was shown was a creature that emits EMP bursts that temporarily shut off the Crawler's light completely.

Players will have their own source of light to rely on in those dire moments. Flares can be thrown on the ground to temporarily illuminate darkened areas. They are rare, though, so you'll have to ration them accordingly. Wilson explains that while some treasures are just a few meters beyond the light of the Crawler and can probably be reached before health runs out, much rarer items can be found much further off the beaten path. Players can risk it by making a pathway of flares, but those flares don't last forever. You'll have to move quickly and survive monster attacks to make it back.

Of course, this is Path of Exile and there always have to be layers of choice-driven progression behind every system.

Of course, this is Path of Exile and there always have to be layers of choice-driven progression behind every system. In the mines, players will find a resource called Azurite that can be spent on upgrading the Crawler and their flares. Players can increase the light radius of both to give them more room to maneuver while fighting, expand their total capacity for Voltaxic Sulphite or flares so they can go on longer delves, or they can boost more passive stats like resistance to the draining darkness.

The Delve map quickly becomes a labyrinth of choices.

And how you explore this infinite dungeon is also up to you. While the levels you delve through are relatively linear, the way they're connected to one another isn't. Your progress through the mines is charted on a map and it's here that you can select the next location that you want to travel towards. You can choose to go on delves that take you deeper into the mine while gradually increasing the difficulty and rarity of items, or you can play it (relatively) safe and travel horizontally to keep the challenge the same.

The mines aren't just a series of caves either, but players will discover entirely new biomes, like lost subterranean cities, that have corresponding rewards. The map will highlight these points of interest so you have objectives to work toward as your push deeper into the mines. And, of course, this is all infinite so players can move through the dungeon in any direction and will always find new areas to explore. Wilson says it'll actually be the first time competitive Path of Exile players will be able to measure their skill against one another since the mines act like a kind of leaderboard. Bragging rights will go to whoever is furthest through the mines when the league eventually ends later this fall.

The league will also introduce socketable currency and crafting items.

That's just the main chunk of stuff coming in Delve, too. The league will also introduce socketable currency and crafting items. Path of Exile's crafting system is hopelessly complex, so I won't bother going into the nitty-gritty of it here, but these crafting items have sockets that you can fill with fossils that add a sense of determinism to the otherwise random crafting process. So, for example, if you wanted to increase your chances of getting a lightning damage modifier on a weapon, you can slot a specific kind of fossil into your crafting item that increases the odds of getting a lightning modifier. It's great because it'll (hopefully) make crafting feel a little less daunting for new players by giving them more deterministic methods while giving hardcore veterans that little extra edge when min-maxing their gear. Then there's the usual addition of new and reworked skills and items to play around with.

If you're a dedicated Path of Exile player, Delve is already a no-brainer. For me, as more of a casual who dips in and out throughout the year, Delve is one league I definitely want to play. I love the tension that its emphasis on light creates—that sense of mystery in not knowing what wonders (and dangers) could be lurking just a little deeper into the mine.