Spellcasting: Zaroth is a 14th-level spellcaster. His spellcasting ability is Intelligence (spell save DC 17, +9 to hit with spell attacks). He has the following wizard spells prepared:

• Cantrips (at will): Chill Touch, Toll the Dead, Mage Hand, Minor Illusion
• 1st level (4 slots): Mage Armor, Shield, Ray of Sickness
• 2nd level (3 slots): Mirror Image, Misty Step, Blindness/Deafness
• 3rd level (3 slots): Counterspell, Animate Dead, Vampiric Touch
• 4th level (3 slots): Blight, Greater Invisibility
• 5th level (2 slots): Cloudkill, Wall of Force
• 6th level (1 slot): Circle of Death

Undead Thralls: When Zaroth casts Animate Dead, he can target one additional corpse, creating another undead. His undead minions add his proficiency bonus to their weapon damage rolls and gain extra hit points equal to his wizard level.

Grim Harvest: Once per turn when Zaroth kills a creature with a spell of 1st level or higher, he regains hit points equal to twice the spell’s level (or three times if it's a necromancy spell).

Dark Lord's Aura (1/Day): As a bonus action, Zaroth emits a 30-foot-radius aura of necrotic energy. Creatures of his choice in the area must make a DC 17 Constitution saving throw, taking 10 (3d6) necrotic damage on a failed save or half as much on a successful one

Multiattack: Zaroth makes two attacks with his Staff of the Necromancer or casts one spell and uses a cantrip.

Staff of the Necromancer: Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 5 (1d6+2) plus 3 (1d6) necrotic damage.

Amulet of the Black Star (1/Day): Zaroth casts Finger of Death without expending a spell slot. The target must make a DC 17 Constitution saving throw, taking 61 (7d8 + 30) necrotic damage on a failed save, or half as much on a successful one. A humanoid killed by this spell rises as a zombie under Zaroth's control.

Shield (1st-level Spell): In response to being hit by an attack, Zaroth raises his AC by 5 until the start of his next turn.

Counterspell (3rd-level Spell): When a creature casts a spell within 60 feet, Zaroth can attempt to interrupt it.