Sunlight Sensitivity. While in sunlight, the deathlock has disadvantage on attack rolls, as well as on Wisdom (Perception) checks that rely on sight.
Unusual Nature. The deathlock doesn't require air, food, drink, or sleep.
Spellcasting. The deathlock casts one of the following spells, using Charisma as the spellcasting ability (spell save DC 13):
At will: detect magic, disguise self, mage armor
1/day each: fear, hold person
Multiattack. The deathlock makes two Life Drain or Grave Bolt attacks.
Life Drain. Melee Weapon Attack: +4 to hit, reach 5 ft., one creature. Hit:6 (1d8 + 2) necrotic damage. The target must succeed on a DC 13 Constitution saving throw, or its hit point maximum is reduced by an amount equal to the damage taken. This reduction lasts until the target finishes a long rest. The target dies if its hit point maximum is reduced to 0.
A Humanoid slain by this attack rises 24 hours later as a zombie under the deathlock's control, unless the Humanoid is restored to life or its body is destroyed. The deathlock can have no more than twelve zombies under its control at one time.
Grave Bolt. Ranged Spell Attack: +5 to hit, range 60 ft., one target. Hit:12 (2d8 + 3) necrotic damage.
The forging of a pact between a warlock and a patron is no minor occasion—at least not for the warlock. The consequences of breaking that pact can be dire and, in some cases, lethal. A warlock who fails to live up to a bargain with an evil patron runs the risk of rising from the dead as a deathlock, a foul Undead driven to serve its otherworldly patron.