Ballistics Expert

This subclass was made by me just because I always wondered why there isn't any subclass for artificer that focuses almost exclusively on firearms, like what do you mean? Firearms were introduced in TCE WITH Artificer. That's why I made this, and I will test it and balance it through my experience with D&D. This subclass is focusing on aggressive supporting from distance and on firearms. Enjoy!

Also there's 2 spells from Xanathar's Guide to Everything in this subclass spell list.

 

1.1 Version Edit:
-added more Defend With Fire abilities (Hollow Point, Power Shot).

1.2 Version Edit:
-changed Ballistics Expert Spells list to better fit the intended subclass role (Polymorh ----> Fire Shield).
-added more Defend With Fire abilities (Blank Bullet).
-changed Casting Marksman's uses (Artificers Infusions Known per day ----> 1 + Intelligence ability modifier) and clarified some rules.
-Sniper's Calm now passively gives 19-20 firearm Critical hit threshold.
-Increased Sharpshooter firearm critical hit threshold to 18-20 (was 19-20) as well as adding new ability Magic Elemental Cartridges.

1.3 Version Edit:
-changed name of two Defend With Fire abilities (Power Shot ----> Slug Shell) and (Blank Bullet ----> Blank Round).
-added more Defend With Fire abilities (AP Round, RIP Round).
-changed description of Defend With Fire - Hollow Point.
-added description of how many Grit Points in Defend With Fire you should have cause I somehow forgot to do this...
-Casting Marksman now passively gives 19-20 firearm critical hit threshold.
-Increased Sniper's Calm firearm critical hit threshold to 18-20 (was 19-20).
-Increased Sharpshooter firearm critical hit threshold to 17-20 (was 18-20).
-changed some of descriptions here and there.

Tool Proficiency / Gunsmith

When you adopt this specialization at 3rd level, you gain proficiency with smith's tools. If you already have this proficiency, you gain proficiency with one other type of artisan's tools of your choice.
You can use smith's and tinker's tools to craft ammunition, modify and create new firearms (DM's discretion).

Ballistics Expert Spells

Starting at 3rd level, you always have certain spells prepared after you reach particular levels in this class, as shown in the Ballistics Expert Spells table. These spells count as artificer spells for you, but they don't count against the number of artificer spells you prepare.

Artificer Level	Spell
3rd	Zephyr Strike, Magic Missile
5th	Branding Smite,  Misty Step
9th	Conjure Barrage,  Lightning Bolt
13th	Arcane Eye,  Fire Shield
17th	Banishing Smite,  Immolation

Arcane Sniper

When you reach 3rd level, your firearm training and your experiments with magic have paid off in two ways:

Weak Spots Knowledge. When you attack with a magic firearm, you can use your Intelligence modifier, instead of Dexterity modifier, for the attack and damage rolls.

Aiming Focus. You can use any magic firearm as arcane focus.

 

Defend With Fire

At 3rd level, you create opportunities for your team by providing them with help from distance or disabling enemies in various ways.
Defend With Fire. You learn two Defend With Fire abilities of your choice. You can use only one per turn. Each use of this ability must be declared before the attack roll is made unless stated otherwise. You learn additional Defend With Fire abilities at 5th, 9th and 15th level. Each time you learn a new Defend With Fire ability, you can also replace one you know with different one. Defend With Fire abilities cost 1 Bonus Action and a Grit Point unless stated otherwise.

Grit. You gain a number of grit points equal to your Wisdom modifier (minimum of 1). You regain 1 expended grit point each time you score a critical hit on your attack roll with firearm, or deal a killing blow with a firearm to a creature with significant threat. You regain all expended grit points after a short or long rest.

Defend With Fire abilities:

AP Round

When you make a firearm attack against a creature, you can spend one grit point to shoot a Armour-Piercing Round making your shot easier to hit, the creature you're targeting has -5 AC for this attack. On a hit the creature takes half the normal damage (doesn't apply to spells from Infused shots).

Blank Round

You can spend 1 grit point to make a non-damaging firearm shot against any creature, if the creature is willing, your hit is guaranteed. Creature that was hit can spend one of its Hit Dice.

Cover

While you are holding a firearm, when a creature you can see within 60 feet of you makes an attack against a creature other than you, you can spend 1 grit point as a reaction to impose disadvantage on the attack roll.

Disarm

When you make a firearm attack against a creature, you can expend one grit point to attempt to shoot an object from their hands. This shot is harder to hit and the enemy you are targeting gets +2 AC. On a hit, the creature suffers normal damage and must succeed on a Strength saving throw against your spell save DC or drop 1 held object of your choice and have that object be pushed 10 feet away from you.

Hollow Point

When you make a firearm attack against a creature, you can expend one grit point to attempt to deal a painful shot to your opponent. This shot is harder to hit and the enemy you are targeting gets +2 AC. On a hit, the creature suffers normal damage and must make a Constitution saving throw against your spell save DC or suffer disadvantage on attacks until the end of their next turn.

RIP Round

When you make a firearm attack against a creature, you can spend one grit point to shoot RIP Round (Radically Invasive Projectile). On a hit, the creature suffers normal damage and prevents any mundane or magical healing on this creature for one turn.

Slug Shell

When you make a firearm attack against a creature, you can expend one grit point to attempt to trip them up and force them back. On a hit, the creature suffers normal damage and must succeed on a Strength saving throw against your spell save DC or be pushed 15 feet away from you.

Casting Marksman

At 5th level, your knowledge in magic and ballistics allow you to infuse firearms and each of its shot with magic. You can infuse your shots with targetable spells a number of times equal to 1 + your Intelligence modifier per day. You regain one use of Infused Shot back with a critical hit using this ability. Each spell must be declared before the attack roll is made. You can use only one spell per attack with firearm. Whether you hit or miss you lose spell slot that was used for infusing the shot. If you score a critical hit, your infused spell (if possible) is casted at a one spell slot level higher. While infusing shot with a spell you ignore the spell's range and use your current firearms range instead.

Your firearm attacks score a critical hit on a roll of 19-20.

Sniper's Calm

Starting at 9th level, you learned to rely on your muscle memory and to ignore stress by focusing on your enemy. Your firearm attacks score a critical hit on a roll of 18-20.

Hold Breath. As a bonus action, you hold your breath giving yourself advantage on your next attack roll on the current turn. You can use this ability only if you haven't moved during this turn, your speed is 0 until the end of the current turn.

Sharpshooter

Starting at 15th level you improve your aiming and bullets with magic. Your firearm attacks score a critical hit on a roll of 17-20.

Magic Elemental Cartridges. You can change your piercing damage from firearms to fire, cold, lightning, acid or poison damage. Choice must be declared before attack roll.