Fishman Karate

Moisture Mastery

At 3rd level you've mastered the principles of Fishman Karate, understanding that moisture exists everywhere—even in the air. You gain the Cold affinity if you do not already have it. If you already have the Cold affinity, all of your cold-affinity-based unarmed/Brawler weapon attacks and Brawl techniques gain an additional die of damage. Your unarmed and Brawler Weapon attacks can originate from anywhere within 15 ft of you and are treated as if you were in that space for features, feats, and techniques that trigger off being adjacent to you during an attack. Additionally, at the start of your turn, you can spend a combo die to extend your Moisture Mastery range even further. Roll the combo die and increase the attack's range by half the rolled amount (rounded up) x 5 feet.

Flowing Water

At 6th level, you've studied the ebb and flow of the tides and learned how to harness their strength to attack the water within a creature's body. 

You gain immunity to the Chilled and Frozen conditions and resistance to Cold and Force damage.

Whenever you deal damage with an unarmed or Brawler weapon attack, once per turn, the opponent must make a Constitution saving throw versus your Brawl save DC. On a failure, they receive a rank of Chilled. Additionally, when you land a critical strike, the target creature gains the Dazed condition. You can now apply the Chilled condition up to twice per turn if you spend a Combo die.

Tsunami

Your strikes embody the wrath of the sea. At 10th level, you can choose between Cold and Force damage whenever you deal damage through any attack, feature, or technique. Additionally, whenever you deal Cold or Force damage, you double your damage modifier. If you would not normally add your damage modifier, you can do so, but do not double it. You can also spend a Combo die to increase the damage die size for that attack by one step (e.g., d6 to d8, d10 to d12).

Avatar of the Sea

You become the embodiment of the ocean. At 14th level, when you successfully hit a creature with an unarmed or Brawler Weapon attack, you can use the moisture surrounding the creature to move them 10 feet in a direction of your choice. This movement does not provoke attacks of opportunity. Additionally, you gain a +1 bonus to your critical range with unarmed and Brawler Weapon attacks and techniques that use either of these as a component. When you score a critical hit, you can spend a Combo die to maximize the damage roll.

Tidebringer

At 18th level, your mastery of moisture and the power of the ocean reaches its zenith, allowing you to manipulate vast amounts of water with unparalleled precision. When you use an unarmed or Brawler Weapon attack, you can unleash a Tidal Surge, a devastating wave of energy that affects all creatures in a 30-foot cone originating from you. All creatures in the area must make a Strength saving throw against your Brawl save DC. On a failure, they take 8d10 Cold or Force damage (your choice) and are knocked prone. On a success, they take half damage and are not knocked prone.

Additionally, your Moisture Mastery range increases to 30 feet, and whenever you spend a Combo die to enhance your range, you roll the Combo die twice and use the higher result.

You are also considered to be under the effects of the Water Walk spell at all times and can breathe underwater without restriction.