Steamsuit Pilot

Prerequisite: Arctech Tinkerer feat, proficient in Arcana and Engineering, character level 7th, access to a technology lab with at least 5,000 gp in components.

Features

Hit Dice: 1d8 per steamsuit pilot level.
Hit Points: 1d8 (or 5) + your Constitution modifier per steamsuit pilot level.

Steam & Steel (1st level). You have designed an arcanoscientific power matrix which you can integrate into a suit of armor as a sort of steam engine, enhancing your strength and ability to move while wearing the armor. Indeed, the power matrix can even let you wear armor larger than your actual body.

If you start with a suit of armor and spend one day and 500 gp in raw materials, you can upgrade that armor with a power matrix and the necessary enchantments and steam valves to operate it. The armor can be your size or larger, up to Large size. Large armor costs the same as medium or small armor, since the main expense
is labor, not materials. The archetypical steamsuit is modified Large full plate, whose only drawback is that it might not fit in some places. (You can certainly build a leather steamsuit, or multiple steamsuits, but you can only operate one at a time.)

A steamsuit is inert without a pilot, and since you designed it for yourself only a creature the same size as you can fit into your suit. You can enter or exit a suit by spending 10 feet of movement. Most suits are designed with masterful locking mechanisms which can be opened either by a key as a bonus action, or by a Dexterity check (DC 20) with thieves’ tools as an action. When you enter the suit you can lock it without spending an action.

You are restrained and blinded while inside a suit that is deactivated. Activating or deactivating the arcane steam engine takes a bonus action. While the engine is active, you are considered proficient in whatever type of armor the suit is. You have a magical link to your steamsuit, so any magical enchantments on what you’re wearing also apply to the steamsuit’s armor. Your steamsuit will typically have hands, so it can wield weapons. If you have a magic weapon, it can wield that weapon, or if it has the same type of weapon and you have the weapon on your person while inside the suit, the weapon the suit wields benefits from that enchantment.

As long as the engine is active, you must maintain the power matrix. As creator of the suit your magical link lets you do this without spending an action as long as you’re inside the suit, even if you’re incapacitated . If anyone else is in the suit, they must make a DC 15 Intelligence check at the start of each turn or else be restrained and unable to use any of the suit’s powers until the start of their next turn.

While in your suit, your Strength score is increased to 19, or to 23 if you are proficient in the type of armor the suit is made out of (i.e., you don’t need the suit to do as much work for you), unless your Strength is already higher. You have double the lifting capacity of a normal creature your size with that Strength. Your suit doesn’t count toward your encumbrance.

You are considered proficient with your suit’s unarmed attacks, which deal 1d6 bludgeoning damage.

At the end of your turn, if you took damage since your last turn while in the suit, make an Intelligence saving throw (DC 10) to keep the suit’s power matrix stable. If you fail three saves, the engine enters a safe mode. This reduces your Strength to its normal amount, imposes a –2 penalty on AC and Dexterity saving throws , and prevents you from taking reactions that require movement.

You can repair the suit during a short rest .

Personal Touches (1st level).  Choose up to ten objects that can be held in one hand (or two-handed objects, which take up two “slots”). You integrate these objects into your suit and can retrieve them and swap between them without limit on your turn, plus they can be hidden from casual view. Sure, it’s obvious you’re in a a halfton clanking shell of steel, but your enemies won’t know you’ve got a shotgun, a musket, a shield, a lantern, a portable ram, and a pair of integrated scimitars. You can still only make use of two hands’ worth of weapons or shields at a time.

Additionally, choose a 1st level spell from the wizard spell list, as long as it does not require an expensive material component. You can use the suit to cast that spell one time, using your Intelligence as the spellcasting ability. Afterward you cannot use it to cast that spell again until you finish a short rest .

At 2nd level, add a 2nd level wizard spell to your capabilities, and at 3rd level add a 3rd level wizard spell. You can cast each spell once between short rests.

If a spell the suit casts has the duration of concentration , whenever you take damage you may make an Intelligence saving throw instead of Constitution saving throw to maintain concentration.

Power Fist (2nd level). Steam pistons in your suit’s arm can launch a devastating punch. When you hit an enemy with your suit’s unarmed strike, you can trigger the power  fist. The attack deals an extra 1d6 damage, and the target must make a Strength saving throw (DC 8 + your proficiency modifier + your Intelligence modifier) or else be shoved 10 feet. You can only use this ability once per turn, and you cannot use it if your suit is in safe mode.

Defensive Shield (2nd level). You can enhance your armor’s resilience with charged wards with limited duration. As a bonus action choose a damage type and gain resistance to that damage type until the end of your next turn. You cannot use this ability if your suit is in safe mode.

Matrix Stability (3rd level). If you suit goes into safe mode, you can repair it by spending an action instead of having to spend a short rest .

Redline Rush (3rd level). On your turn you can overheat your engine to increase your suit’s speed. You double your walking speed for the turn and gain a +5 bonus to all Acrobatics and Athletics checks during this movement. This destabilizes the engine as if you had taken damage, forcing you to make an Intelligence save at the end of your turn, in addition to any save you’d normally make due to taking damage. You cannot use this ability if your suit is in safe mode.

Quick-Don (3rd level). Without spending an action, you can cause your suit to magically collapse into a mechanical object that fits into your palm and weighs only five pounds. You can spend an action or bonus action to cause this object to transform into your suit, and may have the suit form around you and activate the engine. It thus becomes relatively easy to have multiple suits for different occasions.