Path of the Steam Engine

Through augmentation, you have a steam engine built into you. Have fun!

Overheat

Starting at 3rd level when you take this subclass, the immense heat of your steam engine can be used to enhance your rage. The damage type of the bonus damage from rage is now fire damage as your body eminates an aura of heat. Additionally, as a bonus action on any of your turns while you are raging, you can choose to take an overheat level to empower your rage. While you have at least one overheat level, your rage bonus damage deals an extra 2 fire damage per overheat level you have active. While you have at least one overheat level active, at the end of each of your turns you must succeed a constitution saving throw (DC = 13 at first level overheat. Add 2 to the DC for every overheat level above first you have active) or take fire damage equal to your current total rage bonus. This damage cannot be reduced in any way.

4th Level Overheat: If you have 4 or more overheat levels active at a time, you instead take fire damage equal to half your total rage bonus (rounded up) upon succeeding the saving throw at the end of your turn.

7th Level Overheat: If you take a 7th level of overheat or higher on your turn, you must immediately take fire damage equal to the total rage bonus of the respective level of overheat. This damage cannot be reduced in any way.

Full System Vent: If your rage ends while you have at least one overheat level your steam engine performs a full system vent. When this happens, your movement speed is reduced to 0 and you can't take actions until the end of your next turn.

Improved Steam Venting

Starting at 6th level, you have found ways to more efficiently vent steam from your system and use this to your benefit. While in overheat, you now have access to the following actions:

Steam Charge: As a bonus action while in overheat, you may lose an overheat level to double your walking speed as steam is discharged from your system. Additionally, if you make a melee weapon attack against a creature of the same size or smaller than you immediately after taking this action, the creature succeed a strength saving throw or fall prone. The DC of the saving throw is equal to 8 + your strength modifier + your proficiency bonus. If using this action causes you to no longer be in overheat, your rage ends and your engine performs a full system vent.

Steam Blast: As an action while in overheat, you may lose a level of overheat to discharge a highly pressurised burst of steam from your system, taking the shape of a line that is 15 feet long and 5 feet wide. Every creature within this area must succeed a constitution saving throw or take 2d8 + your total overheat bonus worth of fire damage and be knocked prone. The DC of the saving throw is equal to 8 + your strength modifier + your proficiency bonus. If using this action causes you to no longer be in overheat, your rage ends and your engine performs a full system vent.

Steam Propulsion: As a bonus action while in overheat, you may lose an overheat level to jump up to double your jumping distance as steam is discharged from your system. Additionally, add an extra 2 feet to the maximum distance per level of overheat you have active above 1st. If using this action causes you to no longer be in overheat, your rage ends and your engine performs a full system vent.

System Vent Blast

Starting at 10th level, you have modified your engine to weaponize it's regenerative process. Whenever your engine performs a full system vent, steam blasts outward from pipes all across your body. Any creature within 20 feet of you must make a dexterity saving throw (DC = 8 + strength modifier + proficiency bonus). On a failure the targets take 4d10 + your total rage bonus of fire damage, are pushed back 15 feet, and are knocked prone. On a success, the targets take half as much damage and aren't knocked prone.

7th Level Overheat: If you have 7th level overheat or higher, you take half the full damage of this attack.

Overheat Aura

Starting at 14th level, you've found a way to weaponize even more of the excess steam in your system. Whenever you have 4th level overheat or higher, you eminate an aura of heat. Any creature that ends their turn within 10 feet of you takes fire damage equal to half your current total rage bonus. Additionally, any creature that hits you with a melee attack within 5 feet of you takes fire damage equal to your current total rage bonus.