Duet Night Abyss
Complete Weapon & Intron Progression Guide
Introns (I1-I6) and weapons are your biggest power levers in DNA. The challenge is farming Secret Letters efficiently without burning out and knowing which characters to prioritize. This guide gives you the exact order of operations to progress fast as F2P.
Secret Letters
Intron Farming
Weapon Crafting
Commission Routes
How Introns Work
Core mechanic: First ~30 Secret Letters unlock the character. Each additional ~30 Letters unlocks one Intron level. Full I6 requires ~180+ Letters total per character. Farm one character at a time.
| Intron | Letters Needed | Notable Power Spikes |
|---|---|---|
| Unlock | ~30 | Character available to use |
| I1 | ~30 more | First passive improvement |
| I2 | ~30 more | Priority Major buff/utility spike for most characters (Fina, Rebecca, Rhythm) |
| I3 | ~30 more | Moderate improvement - often free from story quests for main chars |
| I6 | ~30 more x3 | Endgame Playstyle-changing effects (Lynn I6 + specific gun combos, Fina personal DPS) |
Step-by-Step Progression
01
Complete Main Story First
Story quests give free Intron levels (up to I3 for Phoxhunter and main characters). This is your fastest early power boost - do not skip story content hoping to farm faster via commissions.
02
Focus One Main Carry + One Support
Pick your main DPS (Rebecca, Psyche, Lynn, or your favorite) and one support. Spend all Secret Letters on these two characters until both hit I2. Spreading Letters across the full roster is the single biggest F2P mistake.
03
Run Covert Commissions Daily
Commissions are your main Letter source. Prioritize Dismantle and Expulsion commission types - fast clears (~20-30 seconds with a decent team). Run these on cooldown every day. They also drop weapon blueprints and upgrade materials simultaneously.
04
Nocturnal Echoes + Weekly Bosses
Nocturnal Echoes gives bonus Letters. Weekly bosses drop Letters and skill materials that Introns require. Do not skip weekly bosses - they are on a one-week reset and cannot be made up.
05
Farm Daily "Thoughts" for Intron Upgrades
Intron unlocking requires Thoughts (character-specific currency) in addition to Letters. Run daily content that drops Thoughts for your priority character. Check the in-game commission menu for which missions drop your target character's Thoughts.
06
Fish Daily for Weapon Materials
Fishing is underrated and heavily rewarded - it drops coins, exp, and weapon crafting materials. Buy the best lures available in the weekly shop. Fishing takes only a few minutes daily and significantly speeds up weapon upgrade timelines.
Weapon Crafting & Upgrading
Good news: All weapons can be fully upgraded regardless of rarity. No weapon is permanently gated. Farm blueprints from commissions, craft at the Forge, upgrade with materials.
W1
Farm Blueprints via Commissions
Blueprints drop as Tier 1 commission rewards. Run commissions focused on your character's preferred weapon type. Check which weapon types give your carry stat bonuses - mismatched weapons lose passive bonuses.
W2
Weapons First, Then Introns
Weapons are cheaper and faster than Introns. For equivalent resource cost, weapons deliver more immediate power. Craft and upgrade priority weapons for your carry first, then redirect resources to Intron grinding.
W3
Level Weapons to 60/70 First
Stop weapon leveling at 60/70 for exp efficiency. Only push past this cap when your character and team are at a level where that marginal gain matters. This applies to character leveling too - 60/70 is the efficient stopping point before content demands higher.
W4
Match Introns with Weapon Synergies
Some Introns create specific weapon combos: Lynn I6 + pizza saw gun for high-burst nuke. Fina I6 amplifies weapon damage. Check your character's I6 description before choosing which weapon to invest in - the wrong weapon negates the Intron effect.
Key Decision Points
Do First
Weapons Before Introns
Weapons are cheaper in equivalent resources (~12-15 Letters worth vs 25-30 for Introns) and deliver faster power improvement. Build priority weapons to 60/70 before pushing Introns past I2.
Commission Choice
Dismantle Over Everything
Dismantle commission type gives the best Letter yield per time spent. Prioritize it when it appears in rotation. Fishing beats capture co-op for material efficiency. Avoid spreading time across all commission types equally.
Letters come naturally over time - don't obsessively grind the same commission all day. A steady daily routine with commissions + fishing + weeklies is more efficient than a burn-out session every few days.
Efficiency Tips
Rhythm I2 is a map-clearing breakthrough - if Rhythm is available in your roster, I2 enables fast AFK exploration clears that save time for other content.
Check Demon Wedge polarity before farming - matching polarities reduces Demon Wedge resource cost. Build wedge sets that match your Intron playstyle, not generic stat-sticks.
Story Introns are free - complete story content fully before farming. Many main characters reach I3 for free, meaning you can skip those Letters and redirect them to supports.
Buy best lures weekly - fishing lure quality affects mat drops. The weekly shop restocks lures - always buy the highest tier available.
Common Mistakes to Avoid
Spreading Letters across multiple characters - The single biggest progression killer. Until your main carry and primary support hit I2, every Letter spent on a side character is a waste.
Leveling fodder characters to 70/70 - Stop at 60/70 for experience efficiency. The XP curve past 60 is steep and not worth the materials until that character is your active priority.
Skipping fishing entirely - Fishing provides coins, exp, and weapon materials that cannot be replicated through combat farming at the same time efficiency. Even 5 minutes daily adds up significantly over a week.
Missing weekly bosses - Weekly bosses provide Letters and skill materials on a hard weekly reset. Missing one week permanently delays your Intron timeline by one cycle.
Ignoring Intron-weapon synergies - Investing in a weapon that does not interact with your character's Intron effects wastes upgrade materials. Check the I6 description before committing to a weapon craft.
Video Guides
Fina Build - Weapons, Introns & Combat AI Setup
Practical example showing how weapon selection and Intron levels combine in a real build
Fina I6 + New Weapon Intron Showcase
Shows the end result of the I6 + weapon synergy system in action