The First Descendant – Best Harris Builds for Mobbing and Bossing

Harris is currently one of the strongest Descendants in The First Descendant. Appropriately built, she turns into a close-range juggernaut who shrugs off damage, spams abilities, and melts even high-resistance bosses like Wall Crasher. Her kit revolves around Toxin, a custom resource that powers her strongest skills and passive buffs, plus huge Defense scaling that lets her turn tank stats into raw damage.

This guide will walk you through how Harris works and how to build her around two core setups:

• Vanguard Build – a fusion / toxic skill build for mobbing and general PvE.
• Battering Ram Build – a boss killer that deletes enemy skill resistances.

1. Harris Overview and Playstyle

Harris is a close-combat ability spammer who trades mana for a custom resource called Toxin. She builds Toxin with her first two skills, then spends it on her third and fourth to unlock huge buffs and extra damage. The catch is that her passive has three different buff tiers, and you want all of them running at once. That means constantly burning and refilling Toxin instead of hoarding it.

Played properly, she feels like a melee caster: you weave short-range attacks, dash through enemies, and repeatedly slam your fourth skill to stack debuffs, all while sitting inside massive shields. The key is staying in the enemy’s face without ever letting your passive buffs or toxin fall off.

Harris works with both melee and firearm-focused setups, depending on which Transcendent Module you equip, but her strongest builds lean into skill damage and melee finishers to abuse her fourth skill thoroughly.

Harris, the Master Engineer.

1.1 Harris’ Strengths and Weaknesses

All in all, Harris rewards players who like to be in the middle of the fight, tracking timers and resource stacks while smashing skills on cooldown. If you enjoy tanky, high-APM characters that scale hard with investment, she is absolutely worth building.

1.1 Harris’s Ability Breakdown

Here is a simplified breakdown of Harris’s kit and how each skill fits into her builds in The First Descendant.

1.1.1 Passive Skill – Internal Toxin Control

Gains or consumes Toxin each time a skill is used. Grants a variety of effects based on the amount of Toxin. Maintaining a certain amount of Toxin for a certain period of time grants Best Condition for each stage.

Harris uses Toxin charges as a custom resource. Spending Toxin moves her through three buff tiers, and all three tiers can exist at the same time if you keep cycling it. At full uptime, you gain cooldown reduction, skill power, melee attack, damage reduction, HP, and Defense, all from this passive alone.

1.1.2 Active Skill 1 – Crushing Charge (Tech)

Charges forward, swinging the NOVA System to deal damage to the target. inflict Towed on enemies within range. Using Crushing Charge consecutively within the Combo Duration enhances the attacks.

A stacking melee combo with six charges and a short cooldown. Using it restores Toxin and recovers ammo for high-cost firearms, and the third hit deals extra damage. It also does bonus damage to Colossi, making it ideal for feeding both Toxin and boss DPS in one button.

Harris’ Crushing Charge skill in The First Descendant.

1.1.3 Active Skill 2 – Site Intrusion (Tech)

Jumps forward and deals damage on landing. Gains Protective Barrier proportional to the number of enemies hit. If no target is hit, the Cooldown of Site Intrusion is partially refunded.

Creates an AoE aura that periodically damages nearby enemies and applies DoT. While it is active, you gain 20% sprint speed, but the skill drains Toxin over time. It is your primary mobbing and movement aura, great for keeping passive buffs rolling while you reposition.

Harris’s Site Intrusion skill in The First Descendant.

1.1.4 Active Skill 3 – Designate Danger Zone (Fusion)

Enters Designate Danger Zone. Consumes Toxin, to deal damage to nearby enemies. Inflicts Spray Hazardous Substance on hit enemies. Grants buffs while in Designate Danger Zone.

A long-range dash you can reactivate to cover significant gaps. If you do not hit an enemy, 80% of the cooldown is refunded so that you can use it aggressively for movement. On hit, you gain a significant barrier based on max HP, more Toxin, and extra skill damage to Colossi. This is your main engagement, repositioning, and barrier-refresh tool.

Harris’ Designate Danger Zone skill in The First Descendant.

1.1.5 Active Skill 4 – Waste Disposal (Fusion)

The NOVA System emits a Cutting Laser over a wide area. Inflicts Toxic Contamination on enemies hit by Cutting Laser. Grants DEF proportional to the number of enemies hit by Cutting Laser.

Harris’s signature nuke. It deals multiple hits of very high skill power in a small radius and boosts your Defense up to +200% while active. Hitting enemies applies a debuff that stacks up to 12 layers; each melee hit consumes a stack to deal additional skill damage. This ability also spends Toxin, so it is central to both your damage and passive cycling.

This kit makes it clear: Harris wants to spam all four skills, not just her ult. You generate Toxin with Skills 1 and 2, spend it on 3 and 4, and in the process keep your passive fully stacked.

Harris’s Waste Disposal skill in The First Descendant.

2. How to Unlock Harris in The First Descendant

Before you start min-maxing Harris builds in The First Descendant, you first need to unlock and research her by collecting the required Descendant materials from the Supermassive Reactor Dungeon, located in Axion Plains. Make sure you plan your farming route around these drops so you do not end up with a half-finished tank when you start pushing harder content.

Below is a full list of materials needed to research Harris and bring her fully online.

All Harris materials you need to unlock her in The First Descendant.

3. Harris Playstyle and Stat Priorities

Harris feels best when you treat her as a rotation-driven brawler. You are constantly cycling between building Toxin, spending Toxin, and refreshing your passive buffs. Standing still or sitting on max Toxin is wasted power; she wants to be in motion, casting something almost every global.

From a stat point of view, she scales extremely well from Defense, Fusion / Toxic Skill Power Ratio, and Cooldown Reduction from her passive, rather than from pure skill cost reduction.

3.1 How to Use Harris Effectively in The First Descendant

To keep Harris’ Passive Skill at full strength at any given time, do the following rhythm:

1. Build Toxin quickly
   • Spam Skill 1 on anything in range to build Toxin and refill ammo.
   • Use Skill 2 aggressively for both movement and resource gain.
2. Spend Toxin deliberately
   • Drop Skill 3 when moving through packs or holding a choke.
   • Use Skill 4 on priority targets, close enough to land all hits.
3. Cycle through all three buff tiers
   • Do not “save” Toxin; spending it is what refreshes your buffs.
   • Aim for near-permanent uptime on cooldown reduction, skill power, and Defense.

When this loop is running smoothly, you can hit very high cooldown reduction values (around ~90% effective in practice), which is why many late-game Harris builds drop external CDR and lean into more damage stats instead.

3.2 Best Harris Stats and What to Prioritize

Across most builds, Harris wants to prioritize:

1. Defense
   • Scales directly with modules like Shield Charge and Battering Ram.
   • With Skill 4 active, she can reach hundreds of thousands of Defense, which turns into both mitigation and damage scaling.
2. Fusion / Toxic Skill Power Ratio
   • Her big skills, especially Skill 4, have very high base skill power.
   • Fusion ratio in particular pairs well with the multi-hit nature of Lava Citadel.
3. HP up to Vanguard threshold
   • For Vanguard builds, you typically only need around 4,000 HP + Shield (for 1.5% roll) or 12,000 HP + Shield (for 0.5% roll) to hit the 600% damage cap on the module’s bonus.
   • Beyond that, more HP has sharply diminishing returns.

With these priorities locked, you can start shaping Harris into either a generalist fusion build for mobbing or a defense monster for boss content.

Harris Showcase in the Forbidden Sanctuary.

4. Best Harris Builds in The First Descendant

Harris really comes alive once you commit to a clear role and build her for use in The First Descendant. Below are two main builds that leverage her strengths in different settings.

4.1 Vanguard Build (Mobbing / General PvE)

This is your everyday Harris build for Void Intercepts like Lava Citadel, mobbing content, and most endgame farming. It leans on Vanguard, Hazmat, and her naturally high skill power to spam abilities and clear packs quickly.

4.1.1 All Items to Use for Harris Vanguard Build

1. External Components
   • Hazmat set for cooldown and DoT synergy; once passive CDR is stable, use Hazmat to free up Reactor stats for Fusion / Toxic skill power ratio instead of flat cooldown.
2. Trigger Modules
   • Vanguard for extra AoE explosions based on HP + Shield (capped around 600%).
   • Shield Charge for converting high Defense into up to 30% extra skill power once you reach roughly 190,000 Defense.
3. Key Components
   • Inversion maxed out.
   • Fusion / Toxic power modules.
   • Duration module as a quality-of-life pick to help maintain all three passive tiers.
4. Weapons
   • Hypernova is an excellent synergy choice: its ability uses sword waves that can consume the 12 stacks from Skill 4’s debuff, turning those stacks into huge bursts of extra skill damage without locking you in long melee animations.
   • Alternatively, a strong melee-friendly AR or launcher if you prefer more conventional gunplay.

4.1.2 Harris Vanguard Build Rotations

• Open with Skill 4 in melee range so all hits connect and apply the full 12-stack debuff.
• Weave Hypernova’s ability or melee hits to consume stacks for bonus skill damage.
• Keep Skill 3 active while moving through packs for AoE and sprint speed.
• Use Skills 1 and 2 on cooldown to regain Toxin, refresh your passive, and keep barriers up.
• Maintain HP at the Vanguard threshold; once you hit the 600% bonus cap, invest further into Defense and Fusion ratio for better scaling instead of more raw HP.

This build thrives in crowd-heavy content where Vanguard’s explosions and Hazmat’s cooldown help you constantly slam abilities. It is forgiving, tanky, and scales very well with gear, making it the best starting point for most Harris players.

Harris Modules for Vanguard Build in The First Descendant.

4.2 Battering Ram Build (Boss / Single-Target)

If you want Harris to break the game truly, this is the build. By stacking Defense and using Battering Ram, she can delete enemy skill resistances, including notorious bosses like Wall Crasher.

Battering Ram’s effect is calculated in a way that directly subtracts from the enemy’s existing skill resistance before the usual damage reduction cap is applied. With enough Defense, Harris can push most enemies’ skill resistances all the way down to zero, ignoring the typical 80% shred cap.

4.2.1 All Items to Use for Harris Battering Ram Build

1. External Components
   • Defense-heavy sets and rolls; Hazmat is still fine, but the priority shifts to maximizing Defense over cooldown.
2. Trigger Modules
   • Battering Ram – the centerpiece of the build, used to wipe out skill resist.
3. Key Components
   • Focus on Defense, Fusion ratio, and duration for buff upkeep.
   • You can skip Defense Neutralization and Toxic Chain Catalyst, because once resist is at zero, those mechanics no longer matter for skill damage.
4. Stats
   • Aim for around 900,000 Defense after activating Skill 4. At this point, Harris can reduce even high-resistance bosses like Wall Crasher (around 222,000 Toxin resist) down to effectively zero.

4.2.2 Harris Battering Ram Build Rotations

• Open with Skill 4 in melee range so all hits connect and apply the full 12-stack debuff.
• Weave Hypernova’s ability or melee hits to consume stacks for bonus skill damage.
• Keep Skill 3 active while moving through packs for AoE and sprint speed.
• Use Skills 1 and 2 on cooldown to regain Toxin, refresh your passive, and keep barriers up.
• Maintain HP at the Vanguard threshold; once you hit the 600% bonus cap, invest further into Defense and Fusion ratio for better scaling instead of more raw HP.

This build is not ideal for mobbing, because juggling passive buffs, Battering Ram timers, and target swapping in a chaotic field of enemies is awkward. But against single targets or very tanky elites, it is terrifying. When executed well, you will see boss HP bars melt the moment Battering Ram is active, and your allies’ skill damage benefits from the same resist reduction.

Harris Battering Ram Modules.

5. Is Harris Worth Building in The First Descendant?

Harris is absolutely worth the investment if you enjoy aggressive, melee-range casters with real build depth. Her Toxin system, multi-tier passive, and Defense scaling give her a toolkit that feels both powerful and technical, and she slots easily into high-end content as either a sturdy mobbing bruiser or a dedicated boss shredder.

The Vanguard build is your go-to for general play, leaning on Hazmat, Vanguard, and fusion scaling to clear waves while staying nearly unkillable. The Battering Ram build is a specialized monster that turns Harris into a raid-level debuffer, erasing enemy skill resistances and supercharging every skill-based teammate around her.

If you are willing to learn her Toxin rhythm and keep an eye on buffs and Defense thresholds, Harris will pay you back with some of the most satisfying, high-impact gameplay in The First Descendant right now.

Harris in The First Descendant.

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