I've created this Gun Mage homebrew Fighter subclass. The intent is to make a fighter that can cast spells by engraving them into bullets that they fire. This is inspired by Gun Mages from Iron Kingdoms as released in the D20 creative commons 3.5 rules. And intended for the Spell Jammer setting for D&D 5e
I intend for the spell progression to follow that of a 1/2 caster. For the full subclass you can check my Gun Mage: Google Doc
Gun Mage Table
Level Prof. Bonus Features 1st 2nd 3rd 4th 5th 3rd +2 Arcane Bullet 3 — — — — 4th +2 3 — — — — 5th +3 4 2 — — — 6th +3 4 2 — — — 7th +3 Ricochet, Adaptable Shot 5 3 — — — 8th +3 5 3 — — — 9th +4 6 3 2 — — 10th +4 Elemental Shot 6 3 2 — — 11th +4 7 3 3 — — 12th +4 7 3 3 — — 13th +5 8 3 3 1 — 14th +5 8 3 3 1 — 15th +5 Snap Shot 9 3 3 2 — 16th +5 9 3 3 2 — 17th +6 10 3 3 3 1 18th +6 Caster Shell 10 3 3 3 1 19th +6 11 3 3 3 2 20th +6 11 3 3 3 2
At 3rd Level you have learned to engrave spells into bullets and add material components to the powder charge in a way that allows firing the bullet to cast the spell. You gain proficiency with Tinkers Tools which you need on hand to craft your Arcane Bullets. You can craft Arcane Bullets in a short or long rest, you can maintain a number of bullets containing spell levels as indicated on the Arcane bullet list. Each Arcane Bullet contains the spell cast when it is created. All consumed Material Components are consumed when the Arcane Bullet is crafted, all somatic and verbal components must be expressed when creating the bullet as well. If a bullet requires a non-consumed Material Component with a gold value, this item must be integrated into your weapon with a tinker tools check with a DC equal to 10 plus the number of material components already integrated into the weapon.
For all spells the target is the impact point of the bullet when fired and range is the range of the firearm. Spells that have a Spell Attack Roll replace this feature with the Weapon Attack Roll of the firearm being used. Spellcasting DC is equal to 8+Ranged Attack Bonus. The spell replaces the standard weapon damage.
Arcane Bullets are loaded as part of the attack action they are fired and ignore the loading quality of a firearm.
At 7th level, you learn how to ensure a missed shot is not wasted, you can ricochet a shot to another target. When you make an attack roll with an arcane bullet and miss, you can use a bonus action to reroll the attack roll against a different target within 60 feet of the original target.
At 7th level, you gain the ability to infuse your normal bullets with magic as they are fired. Any normal bullet you fire counts as magic for the purpose of overcoming damage resistance.
At 10th level you have learned how to infuse the power of the elements into your normal bullets. You can during a short or long rest change the damage type of your Adaptable Shot to: Fire, Acid, Lightning, Thunder, Cold or return it to Piercing.
At 15th level you have gained mastery of your weapon, you can fire a shot intended to make an enemy flinch or seek cover. As a reaction when a creature succeeds on an attack or saving throw within range of an equipped firearm, you can force them to reroll and keep the new roll.
At 18th level you are able to craft your Magnum Opus. During a long rest you can craft one Caster Shell. This is an advanced form of the Arcane Bullet. This bullet can be crafted to contain: Circle of Death, Disintegrate, Harm, or Gravity Fissure. This bullet is so volatile that it will disintegrate at the start of your next long rest from the arcane powers contained within. (Gravity Fissure originates at the barrel of the firearm when fired)