Demonic  Weapons. The undead planetar's weapon attacks are magical. When the undead planetar hits with any weapon, the weapon deals an extra 5d8 necrotic damage (included in the attack).

Innate Spellcasting. The undead planetar's spellcasting ability is Charisma (spell save DC 20). The undead planetar can innately cast the following spells, requiring no material components:

At will: inflict wounds, hellish rebuke

3/day each: blade barrier, dispel evil and good, flame strike, animate dead(undead created this way are under the control of whomever created the undead Planetar)

1/day each: circle of death, banishing smite, dimension door

Magic Resistance. The undead planetar has advantage on saving throws against spells and other magical effects.

Multiattack. The undead planetar makes two melee attacks.

Greatsword. Melee Weapon Attack: +12 to hit, reach 5 ft., one target. Hit: 21 (4d6 + 7) slashing damage plus 22 (5d8) necrotic damage.

Touch of the Fungus Queen (4/Day). The undead Planetar makes a Melee spell attack against a creature within range +12 to hit, 5d8 poison + 5d8 necrotic damage on a hit.