Steam Knight

Steam Knights are not conventional warriors. They are pilots, engineers, explorers, and inventors who entrust their survival to enormous mechanical chassis powered by Haylex, the Ever-Burning Stone.

A Steam Knight chassis is an industrial machine of riveted metal, pistons, boilers, chains, vents, gauges, and mechanical linkages. Its pilot enters through a narrow chute in the rear of the machine and operates the chassis from a protected internal compartment.

Steam Knights continually rebuild their machines throughout their careers. New alloys can alter the properties of their attacks or armor, refined mechanisms can improve mobility and stealth, and advanced engineering allows multiple chassis systems to operate simultaneously.

Though a Steam Knight may appear to be a heavily armored warrior, the true strength belongs to the machine. Outside the chassis, its pilot is considerably more vulnerable.

Excavation Drill

You construct a compact mechanical Excavation Drill designed for mining, digging, and field engineering.

The drill can excavate loose earth, clay, sand, gravel, and similar natural material, and can slowly bore through ordinary stone. You can use it to dig trenches, create small passages, clear collapsed areas, collect geological samples, or extract accessible ore and mineral deposits.

When searching an area where valuable ore, gemstones, crystals, or other mineral deposits might reasonably occur, you can spend 10 minutes surveying and drilling test samples. The DM may ask you to make an Intelligence (Investigation) check to determine whether you locate anything useful.

The Excavation Drill doesn't automatically locate valuable materials, bypass magically reinforced surfaces, or rapidly tunnel through constructed walls and fortifications. The DM determines how long significant excavation requires.

Ore Sense. By examining exposed rock, soil, or mineral formations with the drill's sampling mechanism, you can determine whether the material contains significant quantities of common metal ores. With a successful Intelligence (Investigation) check, you may also identify unusual mineral deposits, gemstones, or other geological materials, at the DM's discretion.

Steam Chassis

Your greatest creation is the Steam Chassis, a compact, heavily armored machine powered by a fragment of Haylex, the Ever-Burning Stone. The chassis surrounds its pilot in a system of metal plating, pistons, gears, clockwork mechanisms, steam pipes, and mechanical controls.

Pilot Chute. A Small creature can enter the chassis through a specially constructed chute in its back. You can enter the chassis as an action while within 5 feet of it. While piloting it, you occupy the chassis's space and are treated as Medium. You can leave the chassis as a bonus action, emerging into an unoccupied space within 5 feet of it.

Armored Chassis. While piloting the chassis, your Armor Class is 18. You gain no benefit from wielding a shield while piloting the chassis.

Powered Frame. While piloting the chassis, its Strength score is 18. Whenever you make a Strength ability check, Strength saving throw, or attack using a chassis weapon, you use the chassis's Strength instead of your own. The chassis counts as one size larger when determining its carrying capacity and the weight it can push, drag, or lift.

Industrial Clamor. The machinery of your chassis is naturally loud. While piloting it, you have disadvantage on Dexterity (Stealth) checks that rely on moving silently.

Haylex Boiler. The chassis is powered by a fragment of Haylex, an extraordinarily rare substance found naturally only within the deepest reaches of the planet. Sometimes called the Ever-Burning Stone, Haylex continuously produces enough heat to power the chassis's closed steam system. Under normal adventuring conditions, you don't need to track fuel or boiler water.

Chassis Integrity. The chassis doesn't have a separate pool of hit points. Your hit points represent both your own endurance and the condition of the machine while you pilot it. If you fall unconscious while piloting the chassis, its systems shut down and you remain inside until you recover or another creature removes you.

Integrated Chassis Systems

Your Steam Chassis is constructed with two integrated mechanical weapons: a pneumatically driven Piston Fist and a powerful Anchor Claw. While piloting your Steam Chassis, these weapons are considered part of the chassis and can't be disarmed.

Piston Fist. The chassis's piston-driven fist delivers crushing blows through a sudden release of mechanical force.

Anchor Claw. The chassis's articulated claw can strike creatures, manipulate objects, grapple enemies, and secure the chassis to terrain.

You are proficient with both chassis weapons. You use the chassis's Strength for their attack and damage rolls.

Chassis Illumination

Your Steam Chassis is fitted with a pair of adjustable Haylex-powered lamps built into its forward chassis. While piloting the chassis, you can activate or extinguish these lamps and adjust their intensity.

The lamps have three illumination settings:

Low Beam. The lamps shed bright light in a 15-foot cone and dim light for an additional 15 feet.

Standard Beam. The lamps shed bright light in a 30-foot cone and dim light for an additional 30 feet.

High Beam. The lamps shed bright light in a 60-foot cone and dim light for an additional 60 feet.

You can activate the lamps, extinguish them, or change their illumination setting without using an action on your turn.

The lamps require the Haylex-powered Steam Chassis to function and produce no light while you are outside the chassis.

Haylex Boiler

At the heart of your Steam Chassis lies a fragment of Haylex, the Ever-Burning Stone. Its ceaseless heat powers a closed boiler system that drives your chassis and allows you to deliberately build and release tremendous amounts of steam pressure.

Pressure Gauge. While piloting your Steam Chassis, you can accumulate Pressure, represented by Pressure Points. You can have a maximum of 5 Pressure Points.

When you enter your Steam Chassis, your Pressure begins at 1, provided the Haylex Boiler is operational.

You gain 1 Pressure Point once per turn when one of the following occurs:

• You hit a creature with your Piston Fist or Anchor Claw.
• You successfully Grapple a creature using Hydraulic Grip.
• A hostile creature hits you with an attack while you are Locked Down.

You can't gain more than 1 Pressure Point during the same turn from these effects.

Pressure Points are expended to operate certain Steam Knight systems. You can't voluntarily spend more Pressure Points than you currently have.

Cooling. Outside combat, the chassis automatically regulates excess boiler pressure. If 1 minute passes without you making an attack, being attacked, or using a Steam Knight feature, your Pressure returns to 1.

Your current Pressure determines the operating state of your boiler:

0 — Dormant. The boiler is depleted of usable pressure.

1–2 — Operating. The chassis functions normally.

3–4 — High Pressure. Certain Steam Knight abilities gain additional effects.

5 — Redline. The boiler is operating at dangerous pressure. Certain abilities become significantly more powerful.

Boiler Vent System

Your Steam Chassis contains directional vents that allow you to rapidly discharge steam accumulated within the Haylex Boiler. When you activate the Boiler Vent System, choose Scald, Pressure Blast, or Purge.

These abilities expend Pressure Points as described in their individual actions.

If a Boiler Vent effect requires a saving throw, it uses your Chassis Save DC:

Chassis Save DC = 8 + your proficiency bonus + the chassis's Strength modifier.

Adaptive Chassis

Your Steam Chassis is built around an adaptive mechanical frame capable of changing its shape and function to suit different environments. Pistons retract, armor plates rotate, gears shift position, and specialized mechanisms deploy as the chassis changes configuration.

At 3rd level, you gain access to Stout Land Form, the chassis's standard terrestrial configuration.

As you advance as a Steam Knight, improvements to the chassis unlock additional configurations, including Subnautical Form and Flight Form.

Unless a configuration states otherwise, changing from one available configuration to another requires an action. You can only benefit from one chassis configuration at a time, and you must be piloting your Steam Chassis to use one.

Field Repair Feature

Your Steam Chassis contains an automated maintenance system capable of repairing damaged plating, straightening bent mechanisms, sealing ruptured pressure lines, and restoring damaged components.

Field Repair Protocol. While piloting your Steam Chassis, you can use an action to initiate a repair cycle, provided you have at least 1 hit point.

When you initiate the repair cycle, your speed becomes 0, and you can't take actions, bonus actions, or reactions until the beginning of your next turn.

At the beginning of your next turn, the repair cycle completes and you regain hit points equal to 1d10 + your Fighter level. You can then act normally.

Once a Field Repair Protocol successfully completes, you can't use it again until you finish a short or long rest.

The hit points restored by this feature represent the chassis repairing damaged armor, mechanisms, pressure lines, and structural components. This restoration is nonmagical.

Subnautical Engineering

You have reconstructed portions of your adaptive chassis to withstand prolonged underwater operation. Reinforced seals protect the Haylex Boiler, ballast chambers regulate the chassis's buoyancy, and specialized propulsion systems allow the machine to maneuver beneath the surface.

You can now select Subnautical Form when using your Adaptive Chassis feature.

When you enter Subnautical Form, the chassis seals around its pilot and deploys its aquatic propulsion and ballast systems. You remain in this configuration until you change configurations, exit the chassis, or become incapacitated.

Chassis Refinements

Beginning at 7th level, your understanding of the Steam Chassis allows you to make substantial modifications to its construction. These modifications, called Chassis Refinements, represent exotic materials, redesigned mechanisms, specialized components, and engineering breakthroughs permanently incorporated into your machine.

You gain one Chassis Refinement of your choice at 7th level. You gain an additional refinement at 10th, 15th, and 18th level.

Unless a refinement states otherwise, its benefits apply whenever you are piloting your Steam Chassis, regardless of its current configuration.

If a refinement requires a saving throw, it uses your Chassis Save DC.

Chassis Save DC = 8 + your proficiency bonus + the chassis's Strength modifier.

Adamantine Bastion

You reinforce the Steam Chassis with adamantine structural members, overlapping armor plates, and massive shock-dampening assemblies designed to withstand catastrophic impacts.

While piloting your Steam Chassis, critical hits against you become normal hits.

In addition, while you have at least 1 Pressure Point, you have advantage on saving throws and ability checks made to resist being Grappled, knocked Prone, or moved against your will.

Finally, when you use a Steam Knight feature that reduces damage you take, you can reroll any 1 rolled on the feature's damage-reduction dice. You must use the new roll.

Advanced Conditioned Plating

You install advanced protective plating, isolated control linkages, redundant stabilization systems, and specialized pilot safeguards throughout your Steam Chassis.

When you select this refinement, choose one of the following conditions: Blinded, Deafened, Frightened, Poisoned, or Prone.

While piloting your Steam Chassis, you are immune to the chosen condition.

Whenever you gain another Chassis Refinement, you can change the condition protected against by this refinement.

Aetherium Frame

You replace portions of the Steam Chassis's internal skeleton with aetherium, an extraordinarily light alloy capable of retaining tremendous structural strength.

While piloting your Steam Chassis:

• Your walking speed increases by 10 feet.

• Any swimming or flying speed granted by your chassis also increases by 10 feet.

• Standing from Prone costs only 5 feet of movement.

• Your chassis's greatly reduced weight allows you to make long jumps and high jumps without a running start.

• When determining your jumping distance, treat your Strength score as 5 higher.

These benefits represent the reduced effective weight and improved responsiveness of the chassis and don't reduce its carrying capacity.

Conditioned Plating

You reinforce your Steam Chassis with specialized internal bracing, sealed mechanisms, redundant controls, and protective plating.

When you select this refinement, choose one of the following conditions: Blinded, Deafened, Frightened, Poisoned, or Prone.

While piloting your Steam Chassis, you have advantage on saving throws made to avoid or end the chosen condition.

Whenever you gain another Chassis Refinement, you can change the condition protected against by this refinement.

Dual Configuration

Your mastery of modular engineering allows your Steam Chassis to maintain two chassis configurations simultaneously.

When you enter your Steam Chassis or change its configuration, you can choose two different chassis configurations available to you instead of one. You gain the benefits and restrictions of both configurations simultaneously.

If two configurations alter the same statistic, such as your speed, use the higher value rather than adding the values together, unless a feature specifically states otherwise.

If the configurations contain contradictory restrictions, the more restrictive rule applies.

You can change one or both of your active configurations whenever you would normally be able to change your chassis configuration.

Infinite Gyroscope

You install an intricate array of counter-rotating flywheels, suspended brass rings, and pressure-driven gyroscopes that continuously calculate and correct the Steam Chassis's balance, orientation, and momentum.

While piloting your Steam Chassis:

• You are immune to the Prone condition.

• You have advantage on ability checks and saving throws made to avoid or escape being Grappled or Restrained.

• You have advantage on ability checks and saving throws made to resist being moved against your will.

• Nonmagical difficult terrain doesn't cost you additional movement.

In addition, when a creature or effect would move you against your will, you can use your reaction to lock the gyroscope. Until the end of the current turn, you can't be moved against your will unless you are Incapacitated.

Lightweight Alloy

You replace portions of your Steam Chassis's heavy structural metal with a rare lightweight alloy without significantly compromising its protection.

While piloting your Steam Chassis, your walking speed increases by 5 feet. Any swimming or flying speed granted by one of your chassis configurations also increases by 5 feet.

In addition, standing from the Prone condition costs you only 5 feet of movement while piloting the chassis.

Pressure Singularity

You install an experimental secondary compression chamber around the Perfected Haylex Engine. Through a network of counter-rotating turbines, pressure accumulators, and regenerative valves, energy normally lost through the chassis's exhaust is captured and returned to the boiler.

While piloting your Steam Chassis, you gain the following benefits:

Regenerative Pressure. Your Pressure Recovery can restore Pressure twice per turn instead of once per turn, but no more than once from the same Steam Knight feature.

Singularity Reserve. When you would gain Pressure while already at your maximum, you can store 1 excess Pressure in the singularity chamber instead. You can store only 1 Pressure this way at a time.

The stored Pressure doesn't count toward your Pressure total and doesn't contribute to Redline.

When you expend Pressure to use a Steam Knight feature, you can expend the stored Pressure in place of 1 Pressure Point from your Haylex Boiler.

The singularity chamber loses its stored Pressure when you exit your Steam Chassis or when your Pressure would normally return to its resting value after a period of inactivity.

Reactive Bastion Plating

You install articulated armor plates, shock-dampening pistons, and mechanically reactive braces throughout your Steam Chassis. When struck, sections of the chassis rapidly shift and interlock around the point of impact.

While piloting your Steam Chassis, when you take damage from an attack, you can use your reaction and expend 1 Pressure Point to reduce the damage by 2d10 + your proficiency bonus.

You decide whether to use this reaction after the damage is rolled. The damage can't be reduced below 0.

Refining Kinesthetics

You rebuild the chassis's moving components using precision-cut gears, dampened pistons, insulated joints, and carefully balanced mechanical linkages.

While piloting your Steam Chassis, Industrial Clamor no longer imposes disadvantage on your Dexterity (Stealth) checks.

In addition, you gain proficiency in Stealth while piloting the chassis. If you already have proficiency in Stealth, you instead add +2 to Dexterity (Stealth) checks made while piloting it.

Reinforced Boiler Housing

You reinforce the Haylex Boiler, pilot compartment, and other vulnerable portions of your Steam Chassis with layered armor and shock-dampening structural supports.

While piloting your Steam Chassis, when you take damage from an attack, you can use your reaction and expend 1 Pressure Point to reduce the damage by 1d10 + your proficiency bonus.

You decide whether to use this refinement after the damage is rolled.

Resonant Core

You install a precisely tuned resonant chamber around the Haylex Boiler, allowing excess mechanical energy to be captured, amplified, and discharged through the Steam Chassis.

While piloting your Steam Chassis, when you hit a creature with your Piston Fist or Anchor Claw, you can expend 1 Pressure Point to create a resonant discharge.

The attack deals an additional 1d8 force damage, and you can push the target up to 10 feet directly away from you if it is Large or smaller.

You can use Resonant Core once per turn.

If the triggering attack already deals force damage, the additional damage from Resonant Core remains force damage.

Resonant Impact Alloy

You incorporate an exotic resonant alloy into the striking surfaces of your Piston Fist and Anchor Claw. When struck, the alloy converts the tremendous mechanical energy of the chassis into a concentrated pulse of magical force.

Whenever you deal bludgeoning or slashing damage with your Piston Fist or Anchor Claw, you can choose for the attack to deal force damage instead of its normal damage type.

You choose the damage type each time you make the attack.

Siege Engine

You rebuild your Steam Chassis's primary combat systems for overwhelming battlefield force. Reinforced actuators, enlarged pressure cylinders, and impact-transfer mechanisms channel the tremendous output of your Haylex Boiler directly into your integrated weapons.

While piloting your Steam Chassis, your Piston Fist and Anchor Claw score a critical hit on a roll of 19 or 20.

In addition, once on each of your turns when you hit a creature with your Piston Fist or Anchor Claw, you can force the target to make a Strength saving throw against your Chassis save DC. On a failed save, choose one of the following effects:

• Breach. The target is pushed up to 15 feet directly away from you.

• Crush. The target is knocked Prone.

• Reposition. If the target is no more than one size larger than you, you move it up to 10 feet to an unoccupied space you can see adjacent to you.

A Huge or larger creature has advantage on this saving throw.

Your Piston Fist and Anchor Claw also deal double damage to objects and structures.

Silent Running

You install near-frictionless bearings, pressure-baffled exhausts, vibration dampeners, and finely balanced mechanical linkages that suppress nearly every unnecessary sound produced by your Steam Chassis.

While piloting your Steam Chassis, your proficiency bonus is doubled for Dexterity (Stealth) checks that use your Stealth proficiency.

In addition, ordinary mechanical operation of your chassis—including walking, turning, and operating its internal mechanisms—can't be heard beyond 30 feet unless you choose otherwise.

Attacking, using the Boiler Vent System, entering Redline, or performing another particularly loud activity can still reveal your position normally.

Aeronautical Engineering

At 10th level, you complete one of the most difficult modifications to the Steam Chassis: sustained aerial operation.

Retractable flight surfaces, directional steam vents, stabilizing gyroscopes, and pressure-driven propulsion systems allow the chassis to leave the ground without sacrificing its combat capabilities.

You can now select Flight Form when using your Adaptive Chassis feature.

When you enter Flight Form, portions of the chassis reconfigure to reduce weight and redirect pressure through its aeronautical propulsion systems. You remain in this configuration until you change configurations, exit the chassis, or become incapacitated.

Pressure Recovery

Beginning at 10th level, improvements to the Haylex Boiler allow your Steam Chassis to reclaim heat and mechanical energy normally lost when powering its systems.

Once per turn, when you expend one or more Pressure Points to use a Steam Knight feature, you recover 1 Pressure Point immediately after that feature resolves if you hit a creature with your Piston Fist or Anchor Claw during the same turn.

Pressure Recovery can't increase your Pressure above your maximum.

Integrated Systems

Beginning at 15th level, your mastery of the Steam Chassis allows you to coordinate its weapons, boiler, vents, hydraulics, and auxiliary mechanisms with extraordinary precision.

Once on each of your turns, immediately after you expend one or more Pressure Points to use a Steam Knight feature, you can activate one of the following systems without requiring its normal bonus action:

• Hydraulic Grip

• Ballast Control, while in Subnautical Form

• A Boiler Vent System function that normally requires a bonus action

You must still meet all requirements for the chosen system and expend any Pressure Points it normally requires.

Integrated Systems can't grant you an additional weapon attack, and you can't use it to activate the same Steam Knight feature that triggered Integrated Systems. Using a system through Integrated Systems doesn't trigger Integrated Systems again.

Perfected Haylex Engine

At 18th level, countless rebuilds, field repairs, experimental alloys, and hard-earned engineering discoveries culminate in the Perfected Haylex Engine, the ultimate evolution of your Steam Chassis's power system.

Your maximum number of Pressure Points increases to 7.

When you enter your Steam Chassis, if you have fewer than 3 Pressure Points, you immediately gain enough Pressure to reach 3.

In addition, you gain the Mastered Redline and Overdrive abilities described below.

Mastered Redline. While you have 5 or more Pressure Points, your Perfected Haylex Engine enters Redline. You remain at Redline until your Pressure falls below 5.

While at Redline:

• Your Piston Fist and Anchor Claw deal an additional 1d6 force damage on a hit.

• Your walking speed increases by 10 feet, as does any swimming or flying speed granted by your chassis.

• When you use Integrated Systems, you can activate two different eligible systems instead of one. You must still pay their Pressure costs.

• You have advantage on Strength checks and Strength saving throws made while piloting your Steam Chassis.

Overdrive. Once on each of your turns while piloting your Steam Chassis, after you take the Attack action and make at least one attack with your Piston Fist or Anchor Claw, you can expend 2 Pressure Points to make one additional attack with your Piston Fist or Anchor Claw as a bonus action.

If you were at Redline when you activated Overdrive, the additional attack has advantage.