Captain Ghostbeard

Ethereal Sight. The captain can see 60 feet into the Ethereal Plane when it is on the Material Plane, and vice versa.

Incorporeal Movement. The captain can move through other creatures and objects as if they were difficult terrain. It takes 5 (1d10) force damage if it ends its turn inside an object.

Withering Scimatar. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 17 (4d8 + 3) slashing damage.

Ghostly Flintlock. Ranged Weapon Attack: +4 to hit, reach 45 ft., one target. Hit: 17 (1d12+9) necrotic damage.

Etherealness. The ghost enters the Ethereal Plane from the Material Plane, or vice versa. It is visible on the Material Plane while it is in the Border Ethereal, and vice versa, yet it can't affect or be affected by anything on the other plane.

Horrifying Visage. Each non-undead creature within 60 feet of the ghost that can see it must succeed on a DC 13 Wisdom saving throw or be frightened for 1 minute. If the save fails by 5 or more, the target also ages 1d4 × 10 years. A frightened target can repeat the saving throw at the end of each of its turns, ending the frightened condition on itself on a success. If a target's saving throw is successful or the effect ends for it, the target is immune to this ghost's Horrifying Visage for the next 24 hours. The aging effect can be reversed with a greater restoration spell, but only within 24 hours of it occurring.

Possession (Recharge 6). One humanoid that the ghost can see within 5 feet of it must succeed on a DC 13 Charisma saving throw or be possessed by the ghost; the ghost then disappears, and the target is incapacitated and loses control of its body. The ghost now controls the body but doesn't deprive the target of awareness. The ghost can't be targeted by any attack, spell, or other effect, except ones that turn undead, and it retains its alignment, Intelligence, Wisdom, Charisma, and immunity to being charmed and frightened. It otherwise uses the possessed target's statistics, but doesn't gain access to the target's knowledge, class features, or proficiencies.

The possession lasts until the body drops to 0 hit points, the ghost ends it as a bonus action, or the ghost is turned or forced out by an effect like the dispel evil and good spell. When the possession ends, the ghost reappears in an unoccupied space within 5 feet of the body. The target is immune to this ghost's Possession for 24 hours after succeeding on the saving throw or after the possession ends.

That's an order! If a skeleton that was summoned by Captain Ghostbeard is attacked, it may make an oppurtunity attack against a hostile creature within 5ft.

Yar! If an enemy enters 5ft of Captain Ghostbeard, or inside the target of a Undead Bombardment then Captain Ghostbeard can make an oppurtunity attack using either Ghostly Flintlock or Withering Scimatar.

Captain Ghostbeard can use 1 legendary action per turn

Loyal to the end. As a bonus action, Captain ghostbeard can summon 1d4 skeletons up to 30 ft away from him, everytime one of these skeletons takes damage, Captain Ghostbeard gains the amount of damage they took as temorary hitpoints.

Summon Soulcoin. As an action, Captain Ghostbeard can summon a golden coin with a skull and crossbones engraved on it, this coin has 1d10 hitpoints, 12 AC, and is vulnerable to fire damage, while this coin is above 0 hitpoints, Captain Ghostbeard cannot take damage. There can only be 1 Soulcoin at a time.

Undead Bombardment.  as a bonus action, Captain Ghostbeard can select one 50ft square that he can see. At the start of his next turn. Ethereal cannons bombard that 50ft square, dealing 3d6 necrotic damage and 2d20 fire damage to all in the radius, except for Captain Ghostbeard.