Last Epoch Dungeon – The Lightless Arbor Guide

The Lightless Arbor is an end-game dungeon that opens up once you reach the late stages of Last Epoch’s campaign.

By participating in various activities like the Arena, Monoliths, and defeating bosses, you can collect Lightless Arbor Keys to access this sunless dungeon.

The Lightless Arbor Dungeon

The Lightless Arbor is appropriately named – it’s perilously dark inside, requiring the bright Pyre Amber crystal for you to navigate tight tunnels and locate enemies.

Surviving the challenging journey leads you to the boss, Mountain Beneath. This formidable foe has two distinct phases with dangerous abilities for you to overcome. Defeating Mountain Beneath grants you access to the Vault of Uncertain Fate.

Finding the Lightless Arbor is easy – once you have a Lightless Arbor Key, travel to the Ruined Era and waypoint at The Surface. Head north to the entrance leading into The Shrouded Ridge, then continue directly north within the ridge until reaching the Lightless Arbor entrance.

The Dungeon Layout

A map of The Lightless Arbor, a Last Epoch Dungeon
Lightless Arbor Dungeon Map – Image credit:

The Lightless Arbor features several large, winding map layouts across its two floors. The maps have an oval shape with various paths snaking through them.

On top of the base layouts, each run has a system of randomized roadblocks that block certain paths while leaving others open. So the route you take through the dungeon will be different every time.

The Lightless Arbor Enemy Types

The enemies you face in the dungeon have a plant theme. There are many Rotweavers – dangerous spellcasting enemies that can stack significant Poison damage on you from a distance with their Weave ability.

They attack rapidly with no cooldown on Weaves, so a group can overwhelm you with poison stacks quickly if you remain stationary. It’s important to keep moving at all times to make it harder for them to continually target you.

A guide showcasing the diverse array of monsters found within the Lightless Arbor, a terrifying Last Epoch Dungeon.
Image credit: Last Epoch Forum

There are also plant-themed Titanspawn enemies and Mountain’s Roots that complement the Rotweavers. While the Titanspawn themselves aren’t too threatening, they can become more difficult to handle when supporting groups of Rotweavers.

On their own, the Titanspawn and Roots deal less damage than the poison mages, but still chip away at your health.

The Mountain Beneath – The Lightless Arbor Boss

The Lightless Arbor Boss - Mountain Beneath
Lightless Arbor Dungeon Boss – Image credit: Last Epoch Forum

The boss of Lightless Arbor is The Mountain Beneath. This is a two phase encounter where the first phase features an invulnerable boss that you need to damage indirectly. In the large arena, there are two pyres on the left and right side, each blocked by a Root Wall.

First Phase

You need to destroy these walls, place your Burning Amber item on the pyres to light them. This causes damage to The Mountain Beneath boss.

However, the boss will also frequently cast Shockwave beams that deal huge damage. It fires them in sequence – left then right side.

You can avoid taking the big hits by positioning yourself on the opposite side to wherever the current beam is. So stand in the center-right area to dodge the left beam, then quickly reposition to the center-left to avoid the right follow up Shockwave.

Once both pyres have burned down after you ignite them, the second phase activates.

Second Phase

The Mountain Beneath will collapse, revealing the true boss – Stone Titan’s Heart.

This boss can be attacked directly. The most dangerous mechanic here is the Spore Beam attack. As soon as you see this beam firing, you need to immediately cross to the opposite side of the arena.

The beams cover a large area but won’t span the entire arena, so with quick reactions you can avoid taking the hit.

Energy Wave is another hazardous attack – it doesn’t deal high damage initially but blankets the arena with poison patches. You’ll likely want to cleanse this poison if you can, as standing in the effect stacks up dangerous damage over time. Aside from those two mechanics, the other abilities of the boss come out slower or are clearly telegraphed making them easier to dodge.

By learning to maneuver around the dangerous poison attacks in phase 1 and then quickly dodging the Spore Beam and Energy Wave attacks in phase 2, you can defeat The Mountain Beneath boss and complete the Lightless Arbor dungeon.

Lightless Arbor Dungeon – Credit: Action RPG

Unique Drops From The Dungeon

There are 4 different Uniques that the Boss can drop, depending on the tier difficulty.

  • Tier 1 and higher may drop the Peak of the Mountain
  • Tier 2 and higher may drop the Foot of the Mountain
  • Tier 3 and higher may drop the Face of the Mountain
  • Tier 4 may drop the Core of the Mountain

The Vault – A High Risk To Reward Ratio

A captivating screenshot of the Last Epoch Dungeon, Lightless Arbor, providing a helpful guide for navigating through this visually stunning video game.
Lightless Arbor Vault – Image credit: Last Epoch Forum

The Vault in Lightless Arbor is a fantastic mechanic that lets you gamble gold for upgraded rewards. If you start to find your coin purse a little light, check out our Last Epoch Gold Farming guide.

You can evaluate risk vs reward in accepting or declining different modifiers that influence item quantity and quality. More expensive choices may return potent gear but drain your wealth quickly without guarantee of success.

When interacting with the Vault, you’ll be presented a series of reward modifiers with options to Accept or Decline. Each offer is priced, so only choose what provides actual value to you.

  • If you Decline an offer, successive options cost more, meaning rerolls grow increasingly expensive.
  • Prices are also impacted by prior choices – securing an ideal set of modifiers can be costly.
  • Sacrificing more Gold may grant stronger rewards from the vault. Outcomes aren’t guaranteed, so strategize risk vs reward through the decisions.
  • If you’re happy with the modifiers (or you’ve used up all your gold), press “Enter Vault” and open the chests inside.
  • You can choose up to 12 modifiers before entering the Vault.

Farming Lightless Arbor Keys

The Arena offers consistent key drops, especially if avoiding Corruption. The key chance boosting modifiers appear on Champions at wave 20+. It’s important to remember that drops are random between various key types.

High Corruption Monoliths will also provide key drops. The higher the Corruption, the better the rates.

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Harriet Gough
Over 20 years' experience as a writer and games journalist. Avid gamer and enjoy a wide range of game genres including MMOs, FPS and RTS. My favorite games include Warframe, Skyrim, Destiny 2, CoD and Age of Empires.

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