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Lost Castle 2’s hardcore roguelike experience doesn’t end after defeating the final boss—it actually intensifies. Once you finish your first playthrough, you’ll meet a new character who reveals that what you just completed was, well, just the beginning. To unlock the full experience, you’ll need to tackle the game on a new difficulty:Ethereal Nightmare.
If you’re still processing the fact that everything you’ve endured so far was nothing compared to the game’s end-game content, you’ll want to know how Ethereal Nightmare works. That’s why we’ve put together this comprehensive guide to help you navigateLost Castle 2’s toughest difficulty setting and maximize your rewards in this brutal game mode.
What Is the Ethereal Nightmare Mode?
Ethereal Nightmare mode is the ultimate end-game difficulty inLost Castle 2. It functions like the game’s New Game Plus, letting you unlock rare resources and gain permanent buffs for your weapons—something not available in the regular mode.
In this mode, you can ramp up the difficulty by adding debuffs to your character, such as reduced Alchemy Elixir capacity or lower HP. These debuffs unlock higher Nightmare Depths, which feature tougher levels with better rewards.
Ethereal Nightmare was introduced on Jul 20, 2025, as part ofLost Castle 2’s biggest update, Nightmare in the Dune. It replaces the previous Hard and Nightmare difficulties, offering a more unique and unpredictable way to experience the game’s NG+ content.
Nightmare Depth
As you ramp up the game’s difficulty through debuffs in the Ethereal Nightmare mode, you’ll unlock higher Nightmare Depths. These end-game levels boost enemy HP and damage, increase the number of monsters you face, and make boss fights even more challenging—all in exchange for rarer rewards likehigh-level Soulstones and Soul Flowers. On top of that, you’re more likely to encounter Champion Relics in the deeper Nightmare Depths. (See below for more details on each of these items.)
Nightmare Depths must be unlocked in chronological order. To reach Nightmare Depth 2, you’ll need to first defeat Depth 1 and so on.
How Should You Unlock the Ethereal Nightmare Mode?
Ethereal Nightmare mode unlocks after you defeatLost Castle 2’s final boss for the first time. Following the boss fight, a short cutscene introduces a new NPC, Nia. She will grant youaccess to the Ethereal Nightmare device in the camp, letting you increase the game’s difficulty or unlock Soul Inscriptions.
You will need awell-built class inLost Castle 2to beat the Ethereal Nightmare mode. I’d recommend going with a tank class for better survivability.
What Rewards Do You Get in the Ethereal Nightmare Mode?
Each time you complete an adventure in Ethereal Nightmare mode, you’ll earn Soulstones, Soul Flowers, and Champion Relics. Like all other rewards, these rare items drop randomly, but their drop rate improves the deeper you go and the higher-level bosses you defeat.
Unlocks buffs for weapons
Unlocks a weapon’s hidden potential
Unlocks a random weapon potential
Here’s what each of these Ethereal Nightmare items does:
Soulstone
Think of Soulstones as primary buffs for your weapons. They can provide general boosts, like increased ATK or SPD, toyour weapon of choice inLost Castle 2. However, before using a Soulstone, you must first unlock that weapon’s initial Soul Inscription. To do this, you’ll need one of the following items: Soul Flowers or Champion Relics.
Soul Flower
When you find a Soul Flower, you can unlock a weapon’s hidden potential. Soul Flowers come in two rarities, and unlocking higher-level potentials (Soul Inscriptions) requires the rarer ones.
Be sure to talk to Nia after each round of the Ethereal Nightmare adventure. She will reward you with Soul Flowers, regardless of whether you succeed or fail in the adventure.
Champion’s Relic
A Champion’s Relic is a memory of a past warrior. When you find one, a random weapon in your inventory will gain a free Soul Inscription. The catch is that you can’t choose how to use them—they’re activated as soon as you pick them up, saving you the Soul Flowers you’d typically spend to unlock a Soul Inscription.
What Is Soulstone Smelting?
A patch in January 2025introduced Soulstone Smelting toLost Castle 2. This feature lets you place ten unwanted Soulstones into a device to receive three new ones in return. If you use high-level Soulstones for smelting, your chances of forging rarer Soulstones are increased.
You’ll likely accumulate many unused Soulstones in your inventory because they’re plentiful in Ethereal Nightmare mode, and each weapon has limited slots for them. That’s why it’s a good idea to forge them into new Soulstones using the smelting feature, giving you a chance to create more powerful buffs.
