Frightful Presence. Any creature , that is not undead or its creator, starts its turn within 5 feet of the Undead Commander must succeed on a DC 14 Wisdom saving throw or be frightened for a minute. At the start of the creature's  turn if the creature is still frightened then that  creature must succeed on a DC 14 Constitution saving throw. If the creature fails three times they become paralyzed.  On a successful saving throw, the creature is immune to the frightful presence for 24 hours.

Turning Defiance. The undead and commander and any undead allies within 40 feet of it have advantage on saving throws against effects that turn undead.

Undying Allies. Undead allies within 20 feet of the Undead Commander get advantage on attack rolls.

Undying Aura. Undead allies within 10 feet of Undead Commander heal for 9 (3d6). 

Causality of War. The Undead Commander can sacrifices one of his allies to regain health equal to half of their total health. (Recharges after 3-4 rounds)

Multiattack. . The undead commander makes two attacks with his longsword or Morningstar. 

Longword. Melee Weapon Attack: +5 to hit, reach 5 ft., one creature. Hit: 9 (1d8 + 5) slashing damage plus 15 (5d6) necrotic damage.

Morningstar. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 9 (1d8 + 5) piercing damage plus 15 (5d6) necrotic damage. 

Follow My Orders. The Undead Commander can forgo his bonus action to allow one undead ally to get a an extra action.

Undying Loyalty. If the Undead Commander is being attack one per round he can command an undead ally within range to block the attack of an opposing creature. The undead ally will than shield the commander form a melee or range attack if able.