Brigade 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.

Grappler. These Doppelgangers have been trained as bouncers and have developed the skills necessary to hold their own in close-quarters grappling. They have advantage on grappling rolls gainst creatures of a smaller size. They have advantage on attack rolls against a creature they are grappling. They can use their action to try to pin a creature grappled by them. To do so, they make another grapple check. If they succeed, they and the creature are both restrained until the grapple ends. Creatures that are one size larger than them don't automatically succeed on chekcs to escape their grapple.

Multiattack. The doppelganger makes two melee attacks.

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.

Mighty Blow. Melee Attack: Attack: +5, reach 5 ft., one target. Hit: 1d12 (1d12) bludgeoning damage.

Bouncer Throw. The Doppelganger can throw a grappled creature 1d20+5 feet in any direction. The creature must pass a dexterity saving throw DC 14 or suffer 1d6 damage for each 10ft thrown. Normal falling damage still applies.