Aura of Doom.

Any creature that starts its turn within 10 feet of the doom lord must make a DC 16 Constitution saving throw, taking 18 (4d8) necrotic damage on a failed save, or half as much damage on a successful one. If the doom lord doesn't have the incapacitated condition, it can suppress or resume this aura at the start of its turn (no action required).

Siege Monster.

The doom lord deals double damage to objects and structures.

Actions

Multiattack.

The doom lord makes two Entropic Greatsword or Entropic Javelin attacks.

Entropic Greatsword.

Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 12 (2d6 + 5) slashing damage plus 10 (3d6) necrotic damage. A creature killed by this attack has its body and everything it is wearing or carrying, except for magic items, reduced to ash.

Entropic Javelin.

Melee or Ranged Weapon Attack: +9 to hit, reach 5 ft. or range 30/120 ft., one target. Hit: 8 (1d6 + 5) piercing damage plus 14 (4d6) necrotic damage. A creature killed by this attack has its body and everything it is wearing or carrying, except for magic items, reduced to ash.

Doomguard Doom Lord