Infernal Tack.

The narzugon wears spurs that are part of infernal tack, which allow it to summon its nightmare companion as an action.

Magic Resistance.

The narzugon has advantage on saving throws against spells and other magical effects.

Actions

Multiattack.

The narzugon makes three Hellfire Lance attacks. It also uses Infernal Command or Terrifying Command.

Hellfire Lance.

Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 11 (1d12 + 5) piercing damage plus 16 (3d10) fire damage. If this damage kills a creature with a soul, the soul rises from the River Styx as a lemure in Avernus in 1d4 hours. If the creature isn't revived before then, only a wish spell or killing the lemure and casting true resurrection on the creature's original body can restore it to life. Constructs and devils are immune to this effect.

Infernal Command.

Each ally of the narzugon within 60 feet of it can't be charmed or frightened until the end of the narzugon's next turn.

Terrifying Command.

Each creature within 60 feet of the narzugon that isn't a Fiend must succeed on a DC 17 Charisma saving throw or become frightened of the narzugon for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. A creature that makes a successful saving throw is immune to this narzugon's Terrifying Command for 24 hours.

Healing (1/Day).

The narzugon, or one creature it touches, regains 100 hit points.

Narzugon