Infernal Gunsmith

Most individuals live their lives in fear. Some spend their years perfecting the arts of swordplay, archery, or pole arm tactics hoping that their skill will be enough to protect them. Martial weapons were seemingly perfected long ago and the true challenge is to master them. However, some individuals weren't satisfied with the innovation of the crossbow. Experimentation with alchemical components and rare metals have unlocked the secrets of controlled explosive force. Eventually, the first firearms were created. But, even then, some individuals still weren't satisfied. The ability to kill one another was perfected, but the ability to slay fiends and demons, that was another story entirely.

This archetype focuses on the ability to design, craft, and utilize powerful, yet dangerous ranged weapons known as firearms. Through innovation and dangerous experimentation, you become a distant force of death on the battlefield. However, not being a perfect science, firearms carry an inherent instability. Eventually, continuously living in fear of fiends and demons, you decided to take your firearms a step further. By imbuing your ammunition with divine power, you would no longer be at the mercy of the fiends and demons. You would become their nightmare. You would become an Infernal Gunsmith.

Bonus Proficiency

At 3rd level, you become proficient with Firearms, allowing you to add your proficiency bonus to attacks made with Firearms.

Demonic Instincts

At 3rd level, through careful study you gain the ability to speak, read, and write either Abyssal or Infernal.

Gunsmithing

At 3rd level, you gain proficiency with Tinker's Tools. You may use them to craft ammunition at half the cost, repair damaged firearms, or even attempt to create new ones. Some extremely experimental and intricate firearms are only available through crafting.

Firearm Properties

Firearms are a new and volatile technology, and as such bring their own unique set of weapon properties. These properties replace the ones presented in the Dungeon Master's Guide. Firearms are ranged weapons.

Reload. The weapon can be fired a number of times equal to its reload score before you must spend an action to reload.

Misfire. Whenever you make an attack roll with a firearm, and the dice roll is equal to the weapon's Misfire Score, the weapon misfires. Whenever a firearm misfires the attack misses. Upon misfiring the number of times equal to the number of attacks granted by your current Fighter level, the weapon cannot be used again until you spend an action to try and repair it. To repair your firearm, you must make a successful Tinker's Tools check (DC equal to 10 - your Intelligence modifier). If your check fails, the weapon is broken and must be repaired out of combat at 25% cost of the firearm or mending can be used to repair your weapon.

Explosive. Upon a hit, everything within 5 feet of the target must make a Dexterity saving throw (DC equal to 8 + your proficiency bonus + your Dexterity modifier) or suffer 1d8 fire damage. If the weapon misses, the ammunition fails to detonate, or bounces away harmlessly before doing so.

Ammunition

All firearms require ammunition to make an attack, and due to their rare nature, ammunition may be near impossible to find or purchase. However, if materials are gathered, you can craft ammunition yourself using your Tinker's Tools at 50% cost of the ammunition. Each firearm uses its own unique ammunition and is generally sold or crafted in batches listed below next to the price.

Firearms 

Name	Cost	Ammo	Damage	Weight	Range	Properties
Bayonet	50 Gold	N/A	1d6 Piercing	3lbs	NA	Special
Hand Mortar	Crafted	10 Gold (5)	2d8 Fire	10lbs	(30/60)	Reload 2, Explosive, Misfire 1
Musket	500 Gold	5 Gold (20)	1d12 Piercing	10lbs	(40/120)	Reload 4, Two-Handed, Misfire 1
Pistol	250 Gold	4 Gold (20)	1d10 Piercing	3lbs	(30/90)	Reload 8, Misfire 1
Shotgun	Crafted	10 Gold (5)	2d8 Piercing	7lbs	(30/90)	Reload 4, Two-Handed, Misfire 1

Radiant Ammunition

At 7th level, you gain the ability to infuse your ammunition with radiant light. Once per turn, when you hit a creature with a ranged weapon attack, you deal an extra 1d10 radiant damage. When you reach 10th level, the extra damage increases to 2d10. When you reach 14th level, the extra damage increases to 3d10.

Blinding Shot. Instead of a normal attack, you can use your action to fire a targeted burst of light to a point you choose within 100 feet. Each creature in a 10-foot-radius sphere centered on that point must make a Dexterity saving throw. A target takes the same amount of damage that Radiant Ammunition deals and is blinded on a failed save, or half as much damage on a successful one.

Demonic Transformation

At 10th level, you gain the ability to polymorph into any fiend or demon of your choice that you're aware of with a CR no greater than that of your current Fighter level. You must spend an action to transform and your equipment merges with your new form, including any items you are currently wielding. While transformed, your stats remain the same but you gain 3d10 temporary hit points and the use of all of the chosen fiend or demon's abilities. Your transformation lasts for 1 minute. When your transformation ends, you lose all remaining temporary hit points. When you reach 14th level, the temporary hit points increase to 4d10. When you reach 18th level, the temporary hit points increase to 5d10.

You can use this ability a number of times equal to your Intelligence modifier. You regain all expended uses upon completing a long rest.

Firearm Mastery

At 15th level, once per day you get to choose a new skill. After choosing one of the skills, you cannot change your choice for that day.

Master Slayer. When killing a creature with a firearm, you gain the ability to use your bonus action to make an additional ranged attack.

Dual Wielder. You gain the ability to wield any firearm in one hand and any one-handed martial weapon in the other.

Ammunition Junkie. You can reload any firearm, regardless of ammunition, as a bonus action instead of an action.

Arcane Gunsmithing

At 18th level, you gain the ability to infuse your ammunition with allies' spells. Once per turn, one of your allies can expend a spell slot of the necessary level to infuse the chosen spell into your next shot. The spell activates upon a successful hit. The spell does not activate upon an unsuccessful hit. Additionally, you gain the ability to use your action to add additional radiant damage to your allies' next attack. The additional radiant damage granted is the equivalent of the amount granted to you within the Radiant Ammunition ability.

You can use this ability a number of times equal to your Intelligence modifier. You regain all expended uses upon completing a long rest.