Karku can use a bonus action to regain hit points equal to 1d10 + 20. He can use this feature three times per long rest.

Karku can make a weapon attack as a bonus action after using Action Surge.

When Karku hits with a weapon attack, he can expend one superiority die to add it to the damage. The target must make a Wisdom saving throw or have disadvantage on attack rolls against anyone other than Karku until the end of his next turn.

When Karku hits with a weapon attack, he can expend one superiority die to add it to the damage. The target must make a Wisdom saving throw or become frightened of Karku until the end of his next turn.

When another creature hits Karku with a melee attack, he can use his reaction and expend one superiority die to reduce the damage by the die roll plus his Dexterity modifier.

When a creature misses Karku with a melee attack, he can use his reaction and expend one superiority die to make one weapon attack against that creature, adding the die to the attack's damage if it hits.

When Karku hits with a weapon attack, he can expend one superiority die to add it to the damage. The target must make a Strength saving throw or fall prone.

When Karku makes an Intelligence, Wisdom, or Charisma check, he can expend one superiority die and add it to the check. He can use this with History, Investigation, or Insight checks.

Karku gains proficiency with all armor, shields, simple weapons, and martial weapons. He also gains proficiency in Strength and Constitution saving throws.

Once per short or long rest, Karku can take one additional action on his turn. At 17th level, he can use this feature twice before resting, but only once on the same turn.

Karku chooses the Battle Master archetype. He gains superiority dice, combat maneuvers, and proficiency with the smith's tools. He begins with four d8 superiority dice, which become d10s at 10th level and d12s at 18th level. He has five superiority dice at 15th level and regains expended dice after a short or long rest.

Karku gains proficiency with smith's tools and one type of artisan's tools or gaming set. He can add a superiority die to an ability check involving a tool he is proficient with.

Karku gains two additional attacks when he takes the Attack action, for a total of three attacks.

When Karku rolls initiative and has no superiority dice remaining, he regains one superiority die.

Karku learns six maneuvers. His maneuvers include Goading Attack, Menacing Attack, Parry, Riposte, Trip Attack, and Tactical Assessment. A maneuver expends one superiority die and uses the relevant saving throw DC of 19 when applicable.

Karku gains proficiency in Wisdom saving throws through the Resilient feat, increasing his Wisdom from 11 to 12.

Karku can reroll a failed saving throw. He can use this feature once per long rest, increasing to twice per long rest at 13th level and three times per long rest at 17th level.

Karku gains seven Ability Score Improvements over his career. He uses them to increase Strength to 20, Constitution to 18, and Dexterity to 17, and takes the Resilient feat for Wisdom saving throw proficiency.

Karku gains proficiency with one additional type of artisan's tools or gaming set, and can add his superiority die to a tool-based ability check.

Karku can spend one minute observing or interacting with another humanoid outside combat to learn whether it has equal, superior, or inferior ability scores, fighter level, armor class, current hit points, or total class levels compared with him.

Karku's superiority dice become d10s. He gains two additional maneuvers, for a total of six.

Karku's superiority dice become d12s.

Karku gains a third attack whenever he takes the Attack action.

Karku retains the practical authority of a former military rank. Soldiers from his homeland recognize his bearing, supply officers understand his clipped orders, and mercenary companies may offer him temporary command or shelter, though his desertion makes such recognition dangerous.