Welcome to The First Descendant Keelan Build Guide for Season 4 Episode 1.
In this guide, we’ll show you how to unleash the full potential of Keelan, the poison snake. From mastering his unique poison-based abilities to selecting the perfect weapons, stats, and modules, this guide covers everything you need to create a truly devastating build for Keelan.
Table of Contents:
- How to play Keelan: A Deep Dive
- Keelan Builds Overview – Modules
- Keelan Trigger Module
- Keelan Ancestor Module
- Arche Tuning for Keelan
- Keelan Equipment Overview
- Keelan Basics
- Keelan’s Story
For builds on other Descendants, visit our The First Descendant Builds Database, or check out the Character Tier List or the Weapon Tier List.
TFD Wiki: We have expanded Alcasthq with tfd.gameslantern.com, a Wiki & Database for anything related to The First Descendant. Use the Character Editor or the Weapon Editor to theorycraft and create builds yourself. Browse Descendants, Weapons, Leaderboard Loadouts or use the Compare Tool. There are plenty of other features you can check out, too!
Here is a quick list of the strengths and weaknesses of the Keelan Build for The First Descendant.
Keelan’s Strengths
Keelan Weaknesses
How to Play Keelan in The First Descendant
In this section, we are going to take a look at how Keelan works in The First Descendant. Keelan excels at both AoE and single-target damage. Learn about his skills in detail in the Keelan’s Skill Explanation section.
Keelan’s AoE Capabilities: Momentum!
Keelan’s skills are great for a lightning-fast playstyle. You can zap around the whole map if you have enough regen. Check out the Keelan Mobbing Build to learn more on how to set it up.
Keelan’s Single Target Damage: Boss Shredding Galore!
Keelan is a great skill-based Descendant that can deal massive burst damage, enough to destroy any colossus within seconds! Make sure that your movement senitivity is high enough so you can move in a zig zag to deal maximum damage! Check out the Keelan Bossing Build.
Keelan’s Equipment: Make Or Break It!
To unlock Keelan’s full potential, you need the right Weapons, Reactors, and External Components:
- Modules: Selecting the right Modules boosts the power of your character the most, this is very important.
- Ancestor Modules: Having a good Ancestor module with the right perks is key to ultimate power for your Descendant.
- Weapons: Keelan is a skill-based Descendant, therefore weapons aren’t that important. However, there are certain weapons that we can use as a “stat stick” to enhance Keelan’s power and mobility even further. Please view the Best Weapons for Keelan section of the build.
- Reactors: Selecting the right reactor can drastically boost your damage. Check out the Best Reactors for Keelan section.
- External Components: These are critical for survivability. Properly configured, they double or triple your HP and DEF. Learn more in the Best External Components for Keelan section.
Building a top-tier The First Descendant Keelan Build requires not only the right modules but also optimized weapons, reactors, and components.
Best Keelan Builds Overview for The First Descendant
Crystallization Catalysts: To unlock the necessary socket slots.- Energy Activator: To increase overall module capacity.
- Gold & Kuiper: Best Gold Farming Method – Best Kuiper Shard Farming Method.
Equipment: I will cover Weapons, Reactors, External Components, Inversion Reinforcements, and Transcendent Modules in the Keelan Equipment section. To maximize the power of any build, you must get the correct items!
| Name | Description |
|---|---|
| Keelan Mobbing Build | Used in any content that requires max AOE damage. |
| Keelan Bossing Build | Used against Colossus fights. |
Keelan Mobbing Build
- Mobbing Build Type: 100%-400% Dungeons, Void Vessel, Disrupt Invasions, farming, anything with hard difficulty.
- Mobbing Build Focus: Optimized for speed, high damage, max range, and good survivability.
The purpose of this Keelan Mobbing Build for The First Descendant is to clear dungeon content like 100%-400% dungeons, Void Vessel or Invasions on hard difficulty.
This Keelan Mobbing Build gives you unlimited dashes to destroy any enemy in your way. Not only that, but you can move through content at lightning speed! The Skill Duration and Skill Cooldown mods are very important for the build to work.
Keelan Mobbing Build Modules Explanation:
- Mobile Strike: Septic Gust deals no damage, grants Adventurer’s Spirit, inflicting Corrosion Acceleration to enemies.
- Skill Expansion: + Skill Effect Range
- Skill Extension: + Skill Duration
- Focus on Singular: + Singular Skill Power Modifier, – Skill Cooldown
- Toxic Amplification: + Toxic Skill Power, – Skill Critical Hit Damage
- Amplification Control: + Skill Effect Range, + Max Shield
- Mid-Air Maneuvering: Allows you to use the Grapple Hook anywhere, even air!
- Battle of Stamina: + Max HP, + Skill Duration
- MP Conversion: – Skill Cooldown, – Max MP
- Focus on Toxic: + Toxic Skill Power, – Skill Cooldown
- Nimble Fingers: – Skill Cooldown
- Maximize Duration: + Skill Duration, – Skill Power Modifier
| Module Slot | Module Name | Mod Level | Socket Type | Crystallized |
|---|---|---|---|---|
| 0 (Trigger Module) | Power Beyond | N/A | N/A | N/A |
| 1 (Skill Module) | Mobile Strike | Max |  Malachite |
No |
| 2 | Skill Expansion | Max |  Rutile |
Yes |
| 3 | Skill Extension | Max | Rutile |
Yes |
| 4 | Focus on Singular | Max | Rutile |
Yes |
| 5 | Toxic Amplification | Max | Rutile |
Yes |
| 6 | Amplification Control | Max | Rutile |
Yes |
| 7 (Sub Module) | Mid-Air Maneuvering | Max | Malachite |
Yes |
| 8 | Battle of Stamina | Max |  Cerulean |
Yes |
| 9 | MP Conversion | Max | Malachite |
Yes |
| 10 | Focus on Toxic | Max | Rutile |
Yes |
| 11 | Nimble Fingers | Max | Malachite |
Yes |
| 12 | Maximize Duration | Max | Rutile |
Yes |
Keelan Bossing Build for The First Descendant
- Bossing Build Type: Colossus fights on hard difficulty.
- Bossing Build Focus: High damage and low cooldown to spam skills and kill boss as fast as possible.
Keelan Bossing Build Modules Explanation:
- Focus on Prey: Increases the number of Projectiles fired and modifies Void Corrosion to target a single enemy.
- Focus on Fusion: + Fusion Skill Power Modifier, – Skill Cooldown
- Hyperfocus: + Critical Hit Damage
- Nimble Fingers: – Skill Cooldown
- Skill Insight: + Skill Critical Hit Rate
- Skill Concentration: + Skill Critical Hit Damage
- Mid-Air Maneuvering: Allows you to use the Grapple Hook anywhere, even air!
- Emergency Measures: + Skill Critical Hit Rate, + Skill Critical Hit Damage
- Focus on Toxic: + Toxic Skill Power, – Skill Cooldown
- Front Lines: + Skill Critical Hit Damage, + Skill Critical Hit Rate
- Spear and Shield:+ DEF, + Skill Power
- MP Conversion: – Skill Cooldown, – Max Mp
| Module Slot | Module Name | Mod Level | Socket Type | Crystallized |
|---|---|---|---|---|
| 0 (Trigger Module) | Power Beyond | N/A | N/A | N/A |
| 1 (Skill Module) | Focus on Prey | Max |  Xantic |
No |
| 2 | Focus on Fusion | Max | Xantic |
Yes |
| 3 | Hyperfocus | Max |  Almandine |
Yes |
| 4 | Nimble Fingers | Max | Malachite |
Yes |
| 5 | Skill Insight | Max | Almandine |
Yes |
| 6 | Skill Concentration | Max | Almandine |
Yes |
| 7 (Sub Module) | Mid-Air Maneuvering | Max | Malachite |
Yes |
| 8 | Emergency Measures | Max | Almandine |
Yes |
| 9 | Focus on Toxic | Max | Rutile |
Yes |
| 10 | Front Lines | Max | Almandine |
Yes |
| 11 | Spear and Shield | Max | Rutile |
Yes |
| 12 | MP Conversion | Max | Malachite |
Yes |
Keelan Trigger Module
You need to first unlock the trigger module slot for each character. Learn how to unlock Trigger Modules in The First Descendant.
For our The First Descendant Keelan Build, you always want to use the Power Beyond trigger module. This gives us a flat 15% Skill Power Increase to all our damage, which is very powerful.
- Mobbing & Bossing: Power Beyond
Keelan Ancestor Module
Ancestor Modules can be slotted once you have acquired them. However, they are only worth it once you have an Ancestor module with good stat rolls on them.
- Keelan Ancestor Module: Adventurer’s Resolution
- Superconductive Cooling Units (Needed to Reroll perks): How to farm
- Must Read: How Ancestor Modules Scale & Examples
Superconductive Cooling Units (Needed to Reroll perks): It is only worth slotting an Ancestor Module if you have good rolls on it; otherwise, it isn’t worth it.
Keelan Mobbing Build
- Ideal Positive Rolls
- Toxic
- Fusion
- Cooldown
- Ideal Negative Rolls
- Max Shield
- DEF
Keelan Bossing Build
- Ideal Positive Rolls
- Toxic
- Fusion
- Skill Critical Hit Rate
- Skill Critical Hit Damage
- Ideal Negative Rolls
- Max Shield
- DEF
Ancestor Module: What to Replace and Why
To slot an Ancestor Module effectively, identify existing modules that share the same primary stat. By replacing a standard module with an Ancestor version that offers similar values, you maintain your core build while gaining its additional unique perks as a ‘free’ bonus.
- How to: Replace a standard module with an Ancestor Module that mirrors its main perk.
- The values should be close; you preferably don’t want to replace a 100% with a 30% value.
- Example 1: If your Ancestor Module provides Skill Critical Hit Rate, replace Skill Insight.
- Example 2: If your Ancestor Module provides Max HP, replace Increased HP.
- Example 3: If your Ancestor Module provides Skill Effect Range, replace Skill Expansion.
- Result: All other perks from the Ancestor Module will basically be a “freebie” and improve your build!
- Helpful Links:
As long as the Ancestor Module reaches a similar value to the one you’re removing, every additional stat on that Ancestor Module becomes a “free” bonus for your build.
Arche Tuning for Keelan
The Arche Tuning System in The First Descendant is important for every Character; it buffs your stats by a good amount. For The First Descendant Keelan, we are focusing on the right and upper right section.
You level up Arche Tuning in the Sigma Sector Dropoff Operation. Mutant Cells also drop there with a small chance.
- Mutant Cell: If you don’t want to swap back and forth you can just use Arche Efficiency Enhancement for both Mobbing and Bossing.
Keelan Equipment Overview in The First Descendant
Equipment is the cornerstone of any successful The First Descendant Build. For Keelan, having the right setup can mean the difference between dominating a dungeon and falling short. This section breaks down the essential equipment types—Weapons, Reactors, and External Components—and explains how they maximize his power.
| Equipment Type | Importance | Key Benefits |
|---|---|---|
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Best Weapon for the Keelan Build in The First Descendant
Because Keelan is a skill-based Descendant, the weapon is not that important. However, you still want to select specific weapons as a “Stat Stick” that give you enhanced mobility and effects to boost your skills further.
Top 3 Weapons for Keelan
| Weapon | Category | Key Features | Why It’s Great for Keelan |
|---|---|---|---|
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Launcher |
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Hand Cannon |
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Scout Rifle |
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Machine Gun |
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Other Useful Weapons
| Weapon | Category | Key Features | Why It’s Great for Keelan |
|---|---|---|---|
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Rocket Launcher |
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Sword |
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Submachine Gun |
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Best Reactor for Nell in The First Descendant
Best Reactor for Keelan in The First Descendant
Selecting the best reactor for Keelan in The First Descendant can significantly enhance his abilities, allowing you to maximize his effectiveness in various scenarios. Not only does the reactor determine your skill damage, but it also gives additional secondary benefits through modifiers. These are often hard to get and take time to grind out!
All of Keelan’s skills are Toxic & Singular/Fusion.
It is hard to get a Reactor with two best in-slot specs. However, you should be able to get a Reactor with at least one good spec. I will highlight the more important spec in bold in the table below.
| Best Reactor | Specs | Key Benefits | Best Builds |
|---|---|---|---|
| Toxic Singularity Reactor |
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Maximizing Colossus Damage. | |
| Toxic Singularity Reactor |
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Overall, the best damage for Mobbing. |
How to find the Location of Reactors
Reactor drop locations change every day. Not many players are aware of this and become confused. Now, there is a reactor search function in-game. Go to the map and press on Difficulty Level Rewards. In here, you can see where all the reactors currently drop.
Note: It is possible that not all reactor types are currently dropping. You have to come back and recheck every day.
If your specified reactor drops in an area, you go there and farm any missions and monsters (Preferably missions with lots of monster spawns). There will be plenty of reactors dropping from monsters all over the place, any monster works. It will take a while to get a good reactor!
Best External Components for the Keelan Build
The best External Components set that works with any of the Keelan Builds is called the Plague Set. It drops in the Sigma Sector Broken Boundary, normal & hard difficulty. Alternatively, you can also use the Slayer set.
Plague is an amazing set because it has 4x Max HP as base stat. Additionally, it obviously also suits Keelan’s skills perfectly. The only thing you should be aware of, that if you are using a Weapon that focuses on crit, then Slayer will be the better option.
External Component Cores: Always go for HP and DEF cores.
Plague Set Bonuses:
- 2 Set Bonus:
- Tech Skill Power +5%
- Singular Skill Power +5%
- 4 Set Bonus:
- Firearm Critical Hit Rate -24%
- Firearm Critical Hit Damage +37%
- Toxic Skill Power +43%
- On acquiring Custom Resource, Toxic Skill Power +22%
Sustain Issues? Alternatively, you can use the Hunter set, which increases your sustain tremendously. You will deal less damage, though. Most of the times sustain issues come from not having the correct substats on your components and not picking up the blue orbs during combat.
| External Component Part | Base Stats | Selective Best Stats | Cores |
|---|---|---|---|
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Max HP |
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Max HP |
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Max HP |
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Max HP |
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Note: You can replace one or two DEF cores with attribute resistance if you fight against specific enemy types.
Inversion Reinforcements Setup for Keelan
You can find the Inversion Reinforcements in the inventory, located on the bottom left side. This changes with every new season and needs to be leveled up again.
At max level, you have unlocked everything. While the last perk is always active in each row, you can only slot three additional perks at the bottom. Here is what you want to prioritize:
- Skill: Perk 1.
- Weapon: None.
- Recovery: Perk 1.
- Survival: Perk 2.
- Season: None.
Keelan Basics in The First Descendant
If it is your first time playing Keelan in The First Descendant, here are some useful things you should know.
How to Unlock Keelan in The First Descendant
Let’s take a quick look at how to unlock Keelan in the First Descendant. To unlock Keelan you have to purchase him from the store, or research him. You need the following items to research Keelan:
- 1x Keelan Enhanced Cells – Drops in Void Vessel normal mode
- 1x Keelan Stabilizer – Drops in Void Vessel normal mode
- 1x Keelan Spiral Catalyst – Drops in Void Vessel normal mode
- 1x Keelan Code – Drops in Void Vessel normal mode
- 400k Credits
When you visit Magisters Anais at the Research Institute you can hover over each item. Then click on Acquisition Info and it will tell you where this specific item drops. You can view an in-depth guide here on How to get X in The First Descendant.
The First Descendant Keelan Skills Explained
In this section, we are going to explain the skills available to our Keelan Build in the First Descendant, how each skill works and the best ways for you to use them.
| Icon | Skill Name | Description |
|---|---|---|
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Void Corrosion | Targets an enemy and fires Void Corrosion, inflicting Acidic Decay on the hit target. Deals additional damage to the enemy with the Acidic Decay. |
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Onslaught | Dashes forward, dealing damage and inflicting Acidic Decay on the pierced enemy. When the skill ends, an explosion occurs, dealing damage to enemies within range. Deals additional damage to enemies with Acidic Decay. |
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Septic Gust | Deals damage and inflicts Acidic Decay on enemies within range. Inflicts Blood Rot on enemies with Acidic Decay, triggering an additional explosion when the skill ends. |
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Tremor | If enemies within range have Acidic Decay, deals additional damage proportional to the amount of Acidic Decay stacks. If enemies within range don’t have Acidic Decay, increases the amount of Onslaught stacks. |
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Erosion (Passive) | Using a skill a certain number of times enhances your abilities and grants you Acidic Infusion Level. |
Void Corrosion
Onslaught
Septic Gust
Tremor
Erosion (Passive)
Smooth Grapple Hook for your Keelan Build
Using the standard Grapple Hook in The First Descendant can be a pain, and it feels kinda frustrating at times. Don’t worry, there is a way better alternative that will make it a joy to use the grappling hook!
It is called the Mid-Air Maneuvering Sub Module. I use this on all my The First Descendant Builds because it improves grappling by so much.
With this Module, you can attach your Grapple Hook to anything, even air! That means you can simply aim towards the sky and Hook up your grapple hook there for guaranteed fast movement!
Here is a guide on how to get the Mid-Air Maneuvering Sub Module in The First Descendant. It won’t take a lot of effort, but it will definitely improve your build and overall gameplay in The First Descendant.
Keelan’s Story in The First Descendant
“What?! The Investigative Corps? Has Alpha lost his mind? The First Descendant Keelan should be utilizing a strong Descendant like you, not putting you in the Investigative Corps! This is a waste!”
Jeremy reacted with disgust after hearing HQ’s decision. Keelan watched him silently and sighed. Keelan Ayodele, was one of the more prolific Descendants to be dispatched on Intercept Battles, usually volunteering for them, had a high success rate. He was an essential Descendant and a vital strategic asset in Intercept Battles, as he used his Arche abilities to manipulate wind and air pressure. He could create favorable variables in battles, such as stopping Colossi movements and altering air currents to redirect incoming attacks.
Although he was dispatched to Intercept Battles on HQ’s orders, Keelan was more driven by his own will. The adrenaline and exhilaration of fighting Colossi in the unpredictable space of the Void had become a driving force for him to fight and gave him a reason to live. However, HQ was concerned about his prolonged exposure to Void Energy, and discouraged him from participating in Intercept Battles, but Keelan was undeterred.
He participated in Intercept Battles as if they were an unbreakable habit, unaware of what the feelings of exaltation were doing to his body. Eventually, a massive amount of Void Energy accumulated in his system, causing abnormalities and altering his Arche Trait. Albion HQ and the Magisters were baffled by the violation of a fundamental rule: “Arche is genetic material inscribed in your DNA and is immutable.” This meant their greatest strategic asset, the Descendants, had been compromised.
They were unsure what problems the transformation of the Arche ability due to Void Energy might cause. In the end, HQ decided to remove Keelan from all major missions, including Intercepts, and assigned him to the Investigative Corps until the matter could be discussed. The work of the Investigative Corps was by no means easy, but for Keelan, who felt alive during life and death Intercept Battles, his new environment bored him to death. Finally, Keelan was summoned to HQ to discuss the situation with Alpha.
“We’ve decided you’re a good fit for augmenting the Void Vessel Special Recon Unit and have changed your assignment to the Void Vessel Special Recon Unit, H.O.U.N.D. You’re an outstanding Descendant, you’ve participated in countless Intercept Battles, you’re familiar with the peculiarities of the Void… and you’re immune to Void Energy, so you check all the boxes. You’ll be a vital asset to H.O.U.N.D.”
Breaking the seriousness of Alpha’s voice, Keelan let out a chuckle of mockery.
“So, I’m a hound specialized for the Void.”
Alpha was set to retort to his cockiness, but Keelan was faster.
“Your wish is my command.”
Keelan felt unbridled joy that he could fight again. It would be in the Void Abyss, in uncharted territory, against enemies he’d never faced before, and he could feel the exhilaration of being alive in the face of that enemy. Of course he was happy. He felt like his heart was beating for the first time in a long time. On his first day in H.O.U.N.D., his training partner, Ines Raya, asked him. “Why are you so happy?” As he replied, he smiled wryly.
“I enjoy the unexpected.”
“With so many people wanting me to live, I have no choice but to do so.” – Dr. Kate
Related Guides for The First Descendant
- The First Descendant Builds Database
- The First Descendant Bunny Build
- The First Descendant Sharen Build
You can also check out our Ultimate Weapons Database for The First Descendant or the Builds Database for The First Descendant.
