Martial Archetype - Buccaneer

While many fighters vie for mastery of the land, a buccaneer is an unrivaled lord or lady of the seas. Both pirates and privateers may find themselves taking up the buccaneer archetype, utilising its blend of direct melee fighting and firearms to dominate ship combat, though their tools and tricks are just as potent on land as they are on the sea.

A buccaneer who grows in strength soon finds the sea responding to them in ways they might never have expected, granting powers beyond the strictly martial and letting them direct the winds and waves almost at will.

The DC for any spells/features granted by Buccaneer is 8 + your proficiency modifier + your Constitution modifier.

Shipsense

At 3rd level, you're a master of the sea. You gain proficiency in the use of Water Vehicles if you didn't have it. Your proficiency bonus for any such checks are doubled. In addition, any checks made to identify aspects of naval vessels such as weakpoints, crew number, or average treasure load/value are made with the same doubled proficiency bonus, regardless of the skill used. You also never get lost at sea, except when due to magical impact, and always have a sense of which way is north while on the open ocean.

Quick Shot

You gain proficiency in the use of firearms. In addition, when you make an attack with a one handed melee weapon you can use a bonus action to draw, fire, and holster a pistol. If you do so in this way you do not require a spare hand to reload it, nor do you incur Disadvantage on the attack for using a ranged weapon within 5' of an enemy creature.

When you reach 10th level in this class, you can ricochet your shot from one creature to another. If you hit a creature with your Quick Shot, you can make a second attack roll against another creature within 15' of the first target.

Deckfighter

From 7th level you're more adept at maintaining your balance on deck, and used to fighting in hectic scenarios. You gain proficiency in either Acrobatics or Athletics, if you didn't already have it, and can no longer be Surprised. In addition, when you make an Opportunity Attack with a one handed melee weapon you can also attempt to Grapple if you have a free hand, or Shove.

Nose for Treasure

You've got an almost sixth (or seventh) sense for the location of treasure and other valuable goods. From 7th level you have advantage on any checks to appraise goods, and if there are any secret treasure caches (which includes, but isn't limited to: gold, magic items, pieces of art, and precious gemstones) within 30' of you, you know their location automatically - though not necessarily how to reach them.

Prayer to the Sea

By reaching 10th level you learn how to utter prayers to the sea and have its vast powers respond in kind. You learn the Gust and Shape Water cantrips. You also can cast each of the following spells once per long rest without requiring material components: Fog Cloud, Gust of Wind, Sleet Storm, and Warding Wind.

At 15th level, you can also cast Control Weather once per long rest.

Locker of the Depths

The cold grip of the sea calls to everyone eventually, and you've learned how to harness this. From 15th level, as an action you can summon a spectral locker to entrap one creature you can see within 60'. This creature must succeed on a dexterity saving throw or be chained inside the locker for 1 minute. The trapped creature can make additional Constitution saving throws at the end of each of their turns to overcome the locker's spell and escape. While inside the locker, they are rendered Unconscious, have total cover from all effects, and are immune to all sources of damage. The locker has an AC of 18 and 150 hit points. Destroying the locker ends the effect early.

The Buccaneer can dismiss the locker freely at will, with no action cost, even when it isn't their turn, and a creature can willingly fail its saving throws, if they so choose.

This feature can be used once before requiring a short or long rest to use again.

Sea's Vengeance

At 18th level your connection to the sea reaches its peak. As an action you can slice open your hand and offer your blood to the great ocean. In doing so, take 2d6 slashing damage, and then cast Storm of Vengeance. The slashing damage cannot be reduced or negated, and pierces through temporary hit points. You are immune to the effects of this spell, as is any ship or vessel you are on (and any other occupants of said vessel).

Instead of taking the damage yourself, you are able to use a sacrifice's blood. If you have reduced a creature with an intelligence score of at least 4 to 0 hit points on your previous turn, you can use their blood (assuming they have any) instead of taking the damage yourself.

This feature can be used once before requiring a long rest to use again.