Doppelganger is a Medium monstrosity with neutral alignment and Challenge Rating 3 in the 2024 SRD. This stat block includes AC 14, 52 hit points, speeds, traits, and actions.
Multiattack - The doppelganger makes two Slam attacks and uses Unsettling Visage if available.
Slam - Melee Attack Roll: +6 (with Advantage during the first round of each combat), reach 5 ft. Hit: 11 (2d6 + 4) Bludgeoning damage.
Read Thoughts - The doppelganger casts Detect Thoughts, requiring no spell components and using Charisma as the spellcasting ability (spell save DC 12).
Unsettling Visage - Wisdom Saving Throw: DC 12, each creature in a 15-foot Emanation originating from the doppelganger that can see the doppelganger. Failure: The target has the Frightened condition and repeats the save at the end of each of its turns, ending the effect on itself on a success. After 1 minute, it succeeds automatically.