Introns are permanent, per‑character power boosts that you unlock by collecting duplicate character materials. They function like constellation/dupe systems in other RPGs: once you recruit a character, additional drops tied to that character convert into Intron upgrades that raise damage, add effects, or otherwise improve a kit. The entire loop is grindable in‑game, with no cash‑only gate on characters or Introns. If you’re just getting started, you can install the game from the Epic Games Store page for Duet Night Abyss: download on Epic Games Store.

Introns 101: the resource chain you need

Every Intron ultimately flows from one repeatable loop:

  • Farm Secret Letter Clues.
  • Exchange 10 Secret Letter Clues for 1 Secret Letter.
  • Spend that Secret Letter to enter a matching Covert Commission (Character, Weapon, or Demon Wedge category).
  • Clear the Commission and choose one of three rewards; the top tier yields Thoughts for a specific character.
  • Use 30 Thoughts to unlock a new character via Reminiscience; excess Thoughts for that character convert to Intron bonuses.

Important constraints:

  • Covert Commissions are level 40. Expect to push the main story and shore up your first build before efficient farming.
  • Missions rotate hourly within each category, changing objectives but not the reward pool tied to the Secret Letter you spent.

Covert Commissions: reward tiers and what to pick

Each cleared Commission presents three items pulled from that Secret Letter’s loot pool. You pick one. For character Introns, you’re hunting Thoughts from the higher tiers.

Tier Typical reward Notes
Gold (I) 10 Thoughts Roughly a 10% drop chance for the 10‑Thoughts option; always take this when it appears.
Silver (II) 2 Thoughts Fallback when Gold doesn’t appear.
Bronze (III) Character EXP materials Least valuable for Introns; take only if neither tier offers Thoughts.
Tip: When target‑farming one unit, always run the Character category with that unit’s Secret Letters to keep your reward pool focused on their Thoughts.

Where to get Secret Letter Clues (and how many)

Once early freebies and pre‑registration rewards dry up, plan a weekly loop around these activities. You need 10 Clues for each Secret Letter, so reliable sources matter.

Activity Secret Letter Clue yield Cadence Notes
Main story and major side quests Variable One‑time per quest Progression unlocks systems and a large chunk of your roster.
Daily objectives 15 Clues Daily Steady baseline; don’t miss these.
Mystic Maze 30 Clues Weekly Roguelike mode; dependable weekly injection.
Immersive Theater Up to 280 Clues Per refresh High yield if you can clear with strong ratings.
Nocturnal Echoes (weekly bosses) Character‑specific Secret Letters Weekly Boss rewards rotate and include the newest unit pool.

Exchange Clues whenever you’re about to run Commissions; keep a small reserve so you can pivot when the hourly mission objectives roll into a favorable layout.

New character cadence: where Introns for fresh units live

Newly released characters follow a rotation that determines where their Secret Letters drop:

  • For the first 28 days, their Secret Letters live in Immersive Theater as featured rewards.
  • After 28 days, those Letters shift into Nocturnal Echoes weekly boss rewards.
  • Afterward, their Secret Letters finally appear in the shop for Secret Letter Clues.

At launch, Psyche headlines Immersive Theater, with a path to earn 65 Psyche Secret Letters and 50 Letters for her signature weapon. During the same window, Nocturnal Echoes bosses reward Letters for Tabethe, Truffle and Filbert, Yale, and Rhythm. If you can consistently secure top ratings in Immersive Theater, this schedule makes targeted farming straightforward; otherwise, waiting for the weekly bosses and shop works fine—every unit eventually lands in the Clue exchange.

Weapons and Demon Wedges: one blueprint, many materials

While you’re farming Introns, you’ll also see Weapon and Demon Wedge drops in their respective Commission categories. You only need each blueprint once to unlock crafting. The ongoing effort is collecting the materials, which drop from the same Secret Letter pool as the blueprint itself. If your build needs a weapon spike to push level‑40 Commissions faster, it can be worth diverting a few Letters to the Weapon category and returning to character farming afterward.

Make the grind efficient: a practical plan

  • Push the main story first. This unlocks core systems, recruits much of the cast, and gets you to the level‑40 breakpoint for Commissions.
  • Invest in one carry to 40. Funneling materials into a single character stabilizes your clear times in level‑40 content.
  • Weekly loop: clear Mystic Maze, Immersive Theater, and Nocturnal Echoes; then mop up dailies. Convert Clues into Secret Letters aimed at your target character.
  • In Commissions, always prioritize Thoughts. Gold (10 Thoughts) when it appears; Silver (2 Thoughts) otherwise. Only take EXP if both higher tiers miss.

With this cadence, you’ll steadily unlock characters at 30 Thoughts and funnel every extra Thought into Introns without wasting stamina on unfocused rewards.

Cosmetics are separate: skins, currency, and pity

Character and weapon progression is grindable; cosmetics use a distinct gacha called Myriad with limited and standard banners. You’ll spend Prismatic Hourglasses on limited‑time outfits and Pristine Hourglasses on the standard pool. Pity works on a hard ceiling: every 10 pulls yields a purple‑rarity item, and 90 pulls guarantees 25 Iridescent Prisms, which can be exchanged for the featured skin. Gold‑rarity items have a 0.3% drop rate and include the featured outfit and Prism bundles; there’s no soft pity, and pity progress is banner‑specific. Some seasonal skins are sold directly for cash as limited shop items.

If you remember nothing else: Introns are a byproduct of disciplined Secret Letter farming. Unlock the systems, hit your weekly pillars, and always choose Thoughts when the game offers them. The upgrades will come.