Blue Dragon Enforcer

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

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

Cunning Action. On each of its turns, the blue dragon enforcer can use a bonus action to take the Dash, Disengage, or Hide action.

Sneak Attack (1/Turn). The blue dragon enforcer deals an extra 14 (4d6) 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 enforcer that isn't incapacitated and the enforcer doesn't have disadvantage on the attack roll.

Innate Spellcasting. The blue dragon enforcer's innate spellcasting ability is Wisdom (spell save DC 12, +4 to hit with spell attacks). It can innately cast the following spells, requiring no material components:

At will: minor illusion, true strike
1/day each: darkness, faerie fire, misty step, suggestion

Multiattack. The blue dragon enforcer makes three melee attacks. Or one melee attack and one ranged weapon attack.

Rapier. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 9 (1d8 + 4) piercing damage.

Hand Crossbow. Ranged Weapon Attack: +7 to hit, range 30/120 ft., one target. Hit: 7 (1d6 + 4) piercing damage.

Uncanny Dodge. The blue dragon enforcer halves the damage that it takes from an attack that hits it. The enforcer must be able to see the attacker.

Retaliate. When the blue dragon enforcers take damage from a creature that is within 5 feet of it, the enforcer can use its reaction to make a melee weapon attack against that creature.