Assassin of Hadar

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 11 (3d6) 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.

Multiattack. The assassin makes two shortsword attacks.

Shortsword. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) piercing damage, and the target must make a DC 15 Constitution saving throw, taking 11 (3d6) necrotic damage on a failed save, or half as much damage on a successful one.

Light Crossbow. Ranged Weapon Attack: +6 to hit, range 80/320 ft., one target. Hit: 7 (1d8 + 3) piercing damage, and the target must make a DC 15 Constitution saving throw, taking 14 (4d6) necrotic damage on a failed save, or half as much damage on a successful one.

Invisibility (Recharge 5-6): The Assassin of Hadar magically turns invisible until it attacks or casts a spell, or until its concentration ends (as if concentrating on a spell).

1. Hadar's Embrace (1/Short or Long Rest): The Assassin of Hadar summons tendrils of dark energy to restrain a creature within 60 feet. The target must succeed on a DC 15 Strength saving throw or be restrained, taking 10 (3d6) necrotic damage at the start of each of its turns while restrained. The target can repeat the saving throw at the end of each of its turns, ending the effect on a success.

2. Shadow Step (1/Short or Long Rest): The Assassin of Hadar magically teleports up to 60 feet to an unoccupied space it can see that is in dim light or darkness.