Duet Night Abyss replaces character gacha with a grind you can plan. The core is the Secret Letter system: you convert Secret Letter Clues into Letters, spend those Letters in Covert Commissions, then pick from a small reward set that can include character unlock items, weapon blueprints, or Demon Wedges. It’s deliberate, repeatable, and entirely free if you have the patience.

Secret Letters in Duet Night Abyss: what they unlock

Secret Letters are single-use items tied to a reward pool: Character, Weapon, or Demon Wedge. After a Covert Commission, the Letter you chose reveals three items from its pool, and you keep one.

  • Characters: you’re looking for “Thoughts.” It takes 30 Thoughts to unlock a specific character.
  • Weapons and Demon Wedges: you need the blueprint once, then the crafting materials (which also drop from the same Letter pool).
  • Introns (character breakthroughs): also farmed via Secret Letters; these upgrades materially boost a character’s power.

Many characters also unlock as you play through the story. Anyone not awarded by the story can be targeted via Secret Letters.

How to get Secret Letter Clues and turn them into Secret Letters

Secret Letters are purchased with Secret Letter Clues at a 10:1 rate. You’ll pick up Clues across core and endgame content, with several reliable anchors each refresh.

Activity What you get Notes
Daily objectives 15 Secret Letter Clues per day Consistent baseline; add up fast over a week
Main story and major side quests Secret Letter Clues Front-load your early stockpile
Mystic Maze (weekly) 30 Secret Letter Clues Roguelike mode with a weekly payout
Immersive Theater (per refresh) Up to 280 Secret Letter Clues High-yield challenge content
Nocturnal Echoes (weekly bosses) Secret Letters for newest characters Rotates which characters are featured

Once you have Clues, exchange 10 of them for one Secret Letter, then choose the Character, Weapon, or Demon Wedge category based on what you’re farming.

Covert Commissions: categories, rotation, and rewards

Covert Commissions are repeatable missions tuned at level 40. You’ll want to push the main story and shore up your starter build before diving in.

  • Categories: Character, Weapon, Demon Wedge. You select a category and consume one matching Secret Letter before starting.
  • Rotation: objectives cycle every hour. The reward pool stays the same; mission types shift between categories.
  • Rewards: after a clear, that Letter reveals three items from its pool; you select one to keep.

Drop quality varies. Gold-tier outcomes like “10 Thoughts” have a 10% chance to appear in the reward trio; lower tiers show up more often and are less valuable. Expect multiple runs to collect enough Thoughts for a specific character.

Unlocking characters with Thoughts and powering up with Introns

Each character requires 30 Thoughts from their Character Secret Letters to unlock. You’ll earn a large chunk of the roster through the campaign, then use Letters to finish anyone missing and to farm Intron upgrades.

Introns function like milestone power bumps for a character. They don’t require spending money, but they do demand repeated Covert Commissions and a steady flow of Secret Letters.

Weapons and Demon Wedges: blueprint first, then materials

For weapons and Demon Wedges, the first chase is the blueprint drop. That single blueprint unlocks the ability to craft the item. After that, it’s a materials grind—and those materials come from the same Secret Letter category that dropped the blueprint, keeping the loop self-contained.

New character availability timeline

Fresh releases follow a staged rollout that makes targeted farming straightforward if you can clear higher-end content.

Stage Where you get their Secret Letters Timing
Launch window Immersive Theater featured rewards 28 days for the newest character
Post-feature Nocturnal Echoes weekly bosses After the 28-day feature period
Standard availability Shop exchange for Secret Letter Clues After rotating through Nocturnal Echoes

At launch, Psyche is the Immersive Theater feature, with 65 Psyche Secret Letters and 50 Letters for her signature weapon available through that track. During the same window, Nocturnal Echoes bosses reward Secret Letters for Tabethe, Truffle and Filbert, Yale, and Rhythm. When Psyche’s 28 days end, her Letters move into Nocturnal Echoes, and another character rotates out.

Cosmetics and skins: gacha currencies, pity, and rates

Characters and weapons aren’t gacha, but cosmetics are. The Myriad menu hosts two banners: Limited and Standard, each with its own currency and a pity counter.

Element Detail
Currencies Prismatic Hourglasses (limited outfits), Pristine Hourglasses (standard)
How to get In-game events, login bonuses; purchasable with Phoxene Plumules
10-pull floor Guaranteed purple-rarity item every 10 pulls
Hard pity 25 Iridescent Prisms after 90 rolls
Prism Exchange Featured skin costs 25 Iridescent Prisms; other items available
Gold-rarity rate 0.3% per roll (featured outfit, 25-Prism bundle, or 50-Prism bundle)
Soft pity No soft pity; odds do not ramp up before hard pity
Pity scope Pity is banner-specific and does not carry over

There are also paid skins sold directly without a pull. The first seasonal example launches as a Christmas-themed outfit at a low introductory price and can be used with any character. Expect the shop to gain more outfits over time.

What a practical farm looks like

Push the story until Covert Commissions feel comfortable at level 40, then settle into a weekly loop: clear Immersive Theater for the largest burst of Secret Letter Clues, grab Mystic Maze’s weekly payout, defeat Nocturnal Echoes bosses for featured Letters, and keep up with dailies for the 15-Clue drip. Convert Clues to Character Letters to chase 30 Thoughts for your target unit, then pivot to Introns or to Weapon/Demon Wedge blueprints and materials.

The system isn’t fast, but it is predictable: clear the right activities, turn Clues into Letters, and let the hour-by-hour Commission rotation feed you the drops you need.