Blades of Bounty Doppelganger

Shapechanger. The doppelganger can use its action to polymorph into a Small or Medium humanoid it has seen, or back into its true form. Its statistics, other than its size, are the same in each form. Any equipment it is wearing or carrying isn't transformed. It reverts to its true form if it dies.

Assassinate. The doppelganger has advantage on attack rolls against any creature that hasn't taken a turn in the combat yet. In addition, any hit it scores against a creature that is surprised is a critical hit

Dueling. When the doppelganger is wielding a melee weapon in one hand and no other weapons, it gains a +2 bonus to damage rolls with that weapon (included in rapier attack).

Archery. The doppelganger has a +2 bonus to attack rolls made with ranged weapons.

Skulk. This creature has advantage on Stealth checks.

Alert. The doppelganger has a +5 bonus to initiative rolls, cannot be surprised while conscious, and unseen attackers do not gain advantage on attacks against it.

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

Sneak Attack. Once per turn, the mercenary can deal an extra 14 (4d6) damage to one creature it hits with an attack if it has advantage on the attack roll. The attack must use a finesse or a ranged weapon. The mercenary doesn't need advantage on the attack roll if another enemy of the target is within 5 feet of it, that enemy isn't incapacitated, and the mercenary doesn't have disadvantage on the attack roll.

Multiattack. The doppelganger makes two melee or ranged attacks.

Rapier, +2. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 13 (1d8 + 9) piercing damage.

Longbow, +1. Ranged Weapon Attack: +10 to hit, range 150/600 ft., one target. Hit: 10 (1d8 + 6) piercing damage.

Read Thoughts. The doppelganger magically reads the surface thoughts of one creature within 60 feet of it. The effect can penetrate barriers, but 3 feet of wood or dirt, 2 feet of stone, 2 inches of metal, or a thin sheet of lead blocks it. While the target is in range, the doppelganger can continue reading its thoughts, as long as the doppelganger's concentration isn't broken (as if concentrating on a spell). While reading the target's mind, the doppelganger has advantage on Wisdom (Insight) and Charisma (Deception, Intimidation, and Persuasion) checks against the target.

Cunning Action. The doppelganger can take the Dash, Disengage, or Hide action as a bonus action.

Blades of Bounty Healing Tonic (x1). As a bonus action, the mercenary can drink a specialised healing tonic manufactured by the alchemists of its gang affiliation. The tonic restores 14 (4d6) hit points and ends the poisoned condition.

Flash. This creature can use any of its actions or bonus actions as reactions.