Culexus Assassin

Assassinate. During its first turn, the assassin has advantage on attack rolls against any creature that hasn't taken a turn. Any hit the assassin scores against a surprised creature is a critical hit.

Evasion. If the assassin is subjected to an effect that allows it to make a Dexterity saving throw to take only half damage, the assassin instead takes no damage if it succeeds on the saving throw, and only half damage if it fails.

Sneak Attack. Once per turn, the assassin deals an extra 42 (12d6) damage when it hits a target with a weapon attack and has advantage on the attack roll, or when the target is within 5 feet of an ally of the assassin that isn't incapacitated and the assassin doesn't have disadvantage on the attack roll.

Antimagic Aura. The Assassin is always under the effect of the Antimagic Field spell.

Mage Slayer. When the assassin damages a creature that is concentrating on a spell, that creature has disadvantage on the saving throw it makes to maintain its concentration.

Innate Spellcasting. The assassin's innate spellcasting ability is Intelligence (spell save 19, +11 to hit with spell attacks). The assassin can innately cast the following spells, requiring no material components:

At will: wrathful smite, tasha's mind whip

3/day each: phantasmal killer, synaptic static, staggering smite

1/day each: maddening darkness, psychic scream, mental prison

Multiattack. The assassin makes two shortsword attacks.

Shortsword. Melee Weapon Attack: +13 to hit, reach 5 ft., one target. Hit: 12 (1d6 + 8) piercing damage, and the target must make a DC 19 Intelligence saving throw, taking 31 (5d6) psychic damage on a failed save, or half as much damage on a successful one.

Light Crossbow. Ranged Weapon Attack: +13 to hit, range 80/320 ft., one target. Hit: 13 (1d8 + 8) piercing damage, and the target must make a DC 19 Intelligence saving throw, taking 31 (5d6) psychic damage on a failed save, or half as much damage on a successful one.