Dragoon

Years of study, training, hardship, danger, and the need for adaption against deadly enemies are what creates a Dragoon fighter. "Those that don't adapt, perish."

Working at some point closely with an artificer, enchanter, smith, firearm specialist, or mentor you have learned the ways of the Cannon Lance. Turning your own Lance into a powerful tool for destruction. 

A Dragoon like any mercenary or soldier is an honorable fighter. Protecting their own and upholding the law or moral codes. Capable of adapting in combat to defend or attack. A Dragoon seeks a good fight against large and dangerous beasts in order to make a living. 

The Cannon Lance

At 3rd level, you no longer have disadvantage when attacking targets within 5 feet of you while using a lance or Cannon Lance.

The Cannon Lance is a magical mechanical lance you are proficient with, as long as your strength is high enough to wield it. The Cannon Lance has the ammunition property and a max range of 15 ft. While wielding a Cannon Lance you can substitute your attack(s) made with the lance portion to instead make an attack with a blast from the magical cannon portion. The damage for this is 1d10 force damage and scales with your level. This damage increases by 1d10 when you reach 5th level (2d10), 11th level (3d10), and 17th level (4d10).

There are two main types of Cannon Lances, Light and Heavy. Both have drums containing the arcane ammunition required to fire the lance, Light has 25 cartridges and Heavy has 50 cartridges. Both recharge 1d4 + your Intelligence modifier cartridges every dawn (using your intelligence modifier here reflects your ability and knowledge of a magical lance to keep it in working order). Reloading after every shot is not needed as long as there is ammunition in the drum, however, if 3 or more shots are fired in one round, the lance needs time to cool and cannot be fired until the end of your next turn.  Light Cannon Lances require a minimum of 16 strength to wield and Heavy Cannon Lances require a minimum of 18 strength to wield.

Acquiring a Cannon Lance is ultimately up to you and your DM but traditionally it can be purchased in any large city. A light Cannon Lance cost 450 GP and a Heavy Cannon Lance cost 700 GP. Alternatively, you may request a wizard or enchanter to turn a normal lance into a Cannon Lance for 50 GP less than the cost of buying one outright, or you yourself can make a Cannon Lance if you have the smith’s or tinker’s tools and are proficient with them you can spend 1d8 days, minus your intelligence modifier and 300 GP to craft a Light Cannon Lance or 550 GP to craft a Heavy Cannon Lance.

Walled Agression

At 7 level, your extensive training with Cannon Lances and similar weapons has granted you the strength to wield and attack with one hand, even when not mounted. Allowing you to don a shield if you wish or use your free hand for other actions such as using an item.

However, wielding Cannon Lances and lances with only one hand decreases the lance’s damage to 1d8 piercing damage. You can of course choose to continue to wield lances with two hands and keep the damage die at 1d12 piercing.

Additionally, if you are wielding a Cannon Lance when you take the Attack action on your turn you can make an additional attack as a bonus action on your turn to fire the Cannon Lance provided you have ammunition to do so. Reminder, if 3 or more shots are fired in one round, the lance needs time to cool and cannot be fired until the end of your next turn.

Focused Blast

At 10th level, when you score a critical hit using your Cannon Lance, you can roll an additional damage die and add it to the extra damage of the critical hit.

Unbreakable

At 15th level, when you are damaged by an attack, you can use your reaction to attempt to block the attack. The damage you take is reduced by 1d10 + your Strength modifier + your Dragoon level. If the damage taken is reduced to 0 you then gain +2 AC until the end of your next turn. You can do so a number of times equal to your proficiency modifier and regain all expended uses after a short rest. 

Crater Blast

At 18th level, you gain the ability to maximize the explosive power of your Cannon Lance. As long as there is available ammunition and the lance isn’t overheated you can use your action to fire a blast from the Cannon Lance that explodes in a 15 ft cone from the you that deals 8d6 Force Damage. The target(s) in this range must then make a Strength saving throw (DC 8 + your proficiency bonus + your Strength modifier) on a failed save they are knocked back 10 ft and rendered prone. On a success, enemies take half damage and are not moved or rendered prone.

The amount of damage done with this attack equals the amount of ammunition consumed.

If the damage done exceeds the amount of ammunition available you instead do damage equal to the ammunition you have, after which you cannot use this ability again until you finish a long rest, even if dawn passes and ammunition is generated.

Otherwise, you may use this Attack as long as you have ammunition and the Cannon Lance is not overheated.