The Truth That Lies Within becomes available immediately after completing The Embers Yet Smolder in Diablo 4 Season 9. As the Horadric storyline intensifies, this quest shifts focus toward dungeon delving, specifically into Nightmare Dungeons containing Horadric Strongrooms.
Though sounding intimidating, this quest is less about skill-based boss fights and more about ideal exploration and farming. Below is what you need to know and do in order to complete The Truth That Lies Within smoothly.
What Is The Truth That Lies Within?
Fundamentally, the quest asks players to go to a Nightmare Dungeon and farm 150 Horadric Knowledge, a special seasonal currency. It is advisable to get it by:
- Defeating Nightmare Dungeon monsters
- Finding and fulfilling Horadric Strongrooms
- Finding Horadric Phials along the way
There is no need to worry about looking for a Nightmare Sigil—ending The Embers Yet Smolder will most often reward you with one, and the game will frequently give you a sigil that guarantees a Horadric Strongroom in the dungeon.
Preparation for the Dungeon
Before you go into the Nightmare Dungeon, check your inventory for any Horadric Spells. Combat modifiers giving bonuses in Strongrooms can help improve your survivability or efficiency. If you have unlocked spells like Celestial Surge or Thunderous Particle, then enable them through the Horadric Spell menu on your character screen.
Although not an endgame-level quest, you would generally be at a good character level with basic survivability and damage skills unlocked. Defense cooldowns, crowd control, and AoE damage will prove useful in dealing with elite enemy groups which are fairly usual in these dungeons.
Inside the Nightmare Dungeon
After inside the Nightmare Dungeon, go through it as normal. You would want to:
Kill enemies as you go – they drop Horadric Phials, which register automatically to your Horadric Knowledge score.
Don’t overlook the Horadric Strongroom – this is a side room with a challenge fight and potentially enormous Knowledge rewards.
Open all the chests and explore all the side rooms – not only for loot, but also to ensure that you’re picking up all Phials possible.
Incidentally, you can finish the quest before you even finish the dungeon. Killing mobs in an attempt to get the 150 Horadric Knowledge is often sufficient. Nevertheless, it’s still worth going on until you find and clear the Strongroom to enable continued progress.
Should You Complete the Strongroom Once the Quest is Done?
Definitely. Even if you’ve already finished The Truth That Lies Within half-way through the dungeon, completing the Strongroom is well worth it:
It rewards extra Horadric Knowledge that you’ll be using later on for season upgrades.
It helps out on future progression for quests like Keepers of the Glen, which you’ll have to go back to Strongrooms anyway.
It’s generally more efficient to complete several objectives in one dungeon trip.
Use this quest as your warm-up to the season grind loop: dungeon > Strongroom > Horadric Knowledge > upgrades > repeat.
After the Quest
As soon as you’ve gained 150 Horadric Knowledge, the quest auto-completes—no point in returning to an NPC right away. The next questline action could be to place or use that knowledge in some fashion, so it’s still worth returning to Cerrigar and speaking with Bryona or visiting the Horadric Archive.
You’ll continue progressing in Season 9’s more nuanced lore, eventually encountering more complex quests with corrupted spirits, haunted relics, and lore-rich rituals.
