Cattelganger

Shapechanger. The cattelganger can use its action to polymorph into a Small or Medium feline 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.

Ambusher. The cattelganger has advantage on attack rolls against any creature it has surprised.

Surprise Attack. If the cattelganger surprises a creature and hits it with an attack during the first round of combat, the target takes an extra 10 (3d6) damage from the attack.

Multiattack. The doppelganger makes two melee attacks.

Scratch. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 7 (1d6 + 4) slashing damage.

Meow. The cattelganger lets out a thunderous meow, surprising any creature who hears it. Any creature within 60 feet that can hear the cattelganger must roll a Charisma saving throw or become Deafened for 30 seconds. While deafened, the cattelganger has advantage on Charisma (Deception, Intimidation, and Persuasion) checks against the target.