The Truths That Lie Within pops up in Diablo 4 Season 9 immediately after completing The Embers Yet Smolder. It will task players with delving into the Horadric Strongrooms found in Nightmare Dungeons. You’ll probably want to have at least a few levels on you before you tackle this challenge, but this isn’t to say you should be level 50 or 60 or anything. Just have a few of your attacks ready, and any defensive cooldowns, if you’ve unlocked them.
However, before you get started, I recommend checking the Horadric Spell section of your inventory and equipping whatever you have available. In my case, it was Celestial Surge and Thunderous Particle, though yours could vary. If you’re ready to tackle Diablo 4’s The Truths That Lie Within, here’s what you need to do.
How to complete The Truths That Lie WIthin in Diablo 4 Season 9
The Truths That Lie Within Steps
- Enter a Nightmare Dungeon
- Gain Horadric Knowledge 0/150 (Find Strongrooms in Nightmare Dungeons)
Thankfully, you don’t have to go hunting for a Nightmare Dungeon because the game should supply you with a key. In addition, it should be a key that guarantees you’ll find a Horadric Strongroom somewhere in the dungeon; so just be diligent, and clear the Nightmare Dungeon, picking up any Horadric Phials you find; those are your reputation items to farm for upgrades.

It’s worth noting that you may not even need to complete the Strongroom before you complete the quest, just by killing the various enemies. Before I got halfway through the Nightmare Dungeon, I had enough Horadric Knowledge, and the quest automatically completed.
The dungeon is guaranteed to have a Horadric Strongroom, though, so take the time to find it, before or after you fight the Nightmare Dungeon’s boss; whichever works for you. I found the Horadric Stronghold first, so I did that before wrapping things up.
Though technically, you may have already completed The Truths That Lie Within in Diablo 4 before completing this dungeon, it may be worth it to you to head back to Cerrigar first. The next quest requires you to seek out a Horadric Strongroom, but you’re going to be grinding these all season anyway. It’s entirely up to you which you do.
If you choose to activate the Horadric Strongroom for this dungeon after completing The Truth That Lies Within, it will count, so you can double-up on efficiency. You'll see The Truths That Lie Within again, as it's the quest name for when you're farming Horadric Knowledge.
Check out our other Diablo 4 guides and features
- Diablo 4 Season 9: All changes since the 2.3.0 PTR
- Season 9: Escalating Nightmares mechanic, explained
- Diablo 4 Season 9 Endgame tier list: Best builds for Pit push and bossing
- Season 9: All Horadric Jewels (known so far)