Cultist Fanatic

Vampire's Sight The cultist's vision is not obscured
by magical darkness.
Death Magic Whenever the cultist deals force
damage, it deals necrotic damage instead

Undying Gift Whenever the cultist is reduced to 0
hitpoints, it can make a Charisma saving throw with a
DC equal to half the damage dealt (minimum 10). It
cannot benefit from this feature if tis takes radiant
damage or if it is hit with a critical hit. On a successful
saving throw, it regains 1 hitpoint instead.

Magical Attacks The cultist fanatic's attacks count as
magical for the purpose of overcoming resistance
Otherworldly Pact The cultist fanatic's spells are
automatically cast at its highest available spell slot
Supernatural Devotion The cultist fanatic has advantage
on saving throws against being charmed or frightened
Sacrificial Offering When the cultist fanatic kills a
creature, they regains one expended spell slot.
Zealous Strikes When the cultist fanatic starts its turn
within 10ft. of another cultist that it can see or hear
within range, the cultist fanatic can make one additional
Pact Blade or Eldritch Blast attack as part of its action.

Spellcasting
The cultist acolyte is an 4th-level spellcaster. Its
spellcasting ability is Charisma (spell save DC 12, +4 to
hit with spell attacks).

Cantrips Toll the Dead Eldritch Blast(see below), Thaumaturgy, Guidance
1st Level Spells (1 slots) Inflict Wounds
2nd Level Spells (2 slots) Hex, False Life, Shadow Blade, Ray of Enfeeblement

Pact Blade. Melee Weapon Attack: +4 to hit, 5ft., one
target. Hit: 7 (1d8+2) piercing damage
Eldritch Blast. Ranged Spell Attack: +4 to hit, 150ft., one
target. Hit: 8 (1d10+2) force damage. This attack is
considered to be a cantrip.
Devotion's Favor(1/short or long rest) The cultist fanatic
can recover all expended spell slots

Deathly Pact Blade When the cultist makes an attack
with its Pact Blade, the target cannot regain hitpoints
until the end of its next turn..

Deathly Blast When the cultist uses Eldritch Blast, the
target cannot regain hitpoints until the end of its next
turn..

Zealous Frenzy The cultist fanatic can expend a spell
slot to deal an additional 7(2d6) force damage on each
of its attacks until the start of its next turn.

Zealous Spree When the cultist fanatic reduces a
creature to 0 hitpoints, it can use its reaction to move
up to half its movement speed and make a Pact Blade
or Eldritch Blast attack against a target in range.

Death's Lash When the cultist takes damage from an
attacker within 60ft. of it, the attacker must succeed a
Constitution saving throw against the cultist's spell
save DC. On a failed saving throw, it takes necrotic
damage equal to the damage taken and the target's
hitpoint maximum is reduced by that amount as well. If
a creature is reduced to 0 hitpoints, it instantly dies. A
creature's hitpoint maximum can be restored by taking
a long rest.

The dead creature turns into a undead provided the body is not destroyed.