Fighting Spirit (3/Day). As a bonus action, the samurai can gain advantage on all attack rolls it makes until the end of its turn.

Indomitable (2/Short Rest). The samurai rerolls a failed saving throw.

Necrotic Aura. Anyone within 30ft of the samurai at the start of their turn takes 1d10 necrotic damage.

Combat Agility. Moves quickly between enemies (100ft movement) when facing more than 1 enemy

Master Swordsman. Gets 1 attack per magical katana wielded.

Magical Long Sword (Katana) Melee Weapon Attack: +8 to hit, reach 5 ft., 1 target. Hit: (1d8+ 10) [Slashing] damage + 2d6 [Elemental] damage. 

Parry. The samurai zombie adds 8 to its AC against one melee attack that would hit it. To do so, the samurai must see the attacker and be wielding a melee weapon.

Legendary Actions can only be used when reduced below half health. 3/day

Perfect Parry (1 reaction). After any physical attack hits and damage is rolled absorb the damage into a blade and return it to the attacker.

Two Handed Attack (1 Action). Double the damage of the attack.