Blackstar Knight

Immutable Form. The blackstar knight is immune to any
spell or effect that would alter its form.
Magic Resistance. The blackstar knight has advantage on
saving throws against spells and other magical effects.
Magic Weapons. The blackstar knight’s weapon attacks are
magical.

Multiattack. The blackstar knight makes four melee attacks
in any combination.
Deathsword. Melee Weapon Attack: +11 to hit, reach 5 ft.,
one target. Hit: 14 (2d6 + 7) slashing damage plus 9 (2d8)
necrotic damage. If the target is a creature, it must succeed
on a DC 19 Wisdom saving throw or be deathmarked. While
deathmarked, a creature takes 9 (2d8) necrotic damage at
start of each of its turns. A creature can use an action to
repeat the saving throw on each of its turns, ending the
effect on itself on a success.
Slam. Melee Weapon Attack: +11 to hit, reach 5 ft., one
target. Hit: 16 (2d8 + 7) bludgeoning damage. If the target
is a creature, it must succeed on a DC 19 Strength saving
throw or be knocked prone.
Blackstar Lightning. Ranged Spell Attack: +8 to hit, range
120 ft., one creature. Hit: 45 (10d8) necrotic damage and
each other creature within 10 feet of the target takes 9
(2d8) necrotic damage. Each creature that takes damage
must succeed on a DC 19 Constitution saving throw or be
stunned until the end of its next turn.

Undying Duty (1/Day). When the blackstar knight is reduced
to 0 hit points, it can target any number of creatures within
10 feet of it, dealing 11 (2d10) necrotic damage to each
undead and 5 (1d10) necrotic damage to all other creatures,
regaining lost hit points equal to the total damage dealt.

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