Doppelganger 5e: Read Thoughts, the First-Round Ambush and How to Unmask One

A doppelganger is a CR 3 Medium Monstrosity with AC 14, 52 hit points and two Slam attacks at +6. It can turn into a Small or Medium humanoid, read surface thoughts, and is immune to being Charmed. In the 2014 rules it is an ambusher: against a creature it surprises, it attacks with Advantage and adds 3d6 damage. The 2024 doppelganger always attacks with Advantage in the first round of a combat, hits harder (11 per Slam instead of 7), shape-shifts as a bonus action, and gains Unsettling Visage, a fear burst.

Table of Contents

• •Doppelganger Stat Block (2014)
• •The Doppelganger in the 2024 Rules
• •How the Doppelganger Fights
• •Running a Doppelganger Encounter
• •How Players Beat a Doppelganger
• •Doppelganger Encounter Ideas
• •Frequently Asked Questions

Doppelganger Stat Block (2014)

The doppelganger from SRD 5.1:

How its forms work in each edition:

Two things stand out. Its statistics don't change, so it never has to drop the disguise to fight. And because gear isn't transformed, a doppelganger copying a guard needs the guard's actual uniform, which gives investigators a trail: a missing coat, a stolen badge.

Read Thoughts (2014) is an action with a 60-foot range and no saving throw, and nothing in the text alerts the target. While the doppelganger keeps concentration, it has Advantage on Insight, Deception, Intimidation and Persuasion checks against that creature. Its Deception is already +6. Three feet of wood or dirt, 2 feet of stone, 2 inches of metal or a thin sheet of lead blocks it.

The Doppelganger in the 2024 Rules

SRD 5.2.1 keeps CR 3 (700 XP), AC 14, 52 hit points and the Charmed immunity, and rebuilds the rest.

What changes at the table:

• •Surprise stops mattering. Under 2014 rules a surprised creature can't move or act on its first turn, and the doppelganger's bonus damage depends on surprise. In 2024, surprise only means Disadvantage on the Initiative roll, and the doppelganger's edge sits in the Slam itself: Advantage in the first round of each combat whether or not anyone was fooled.
• •Mind reading gets riskier for it. Detect Thoughts reads only what's on the target's mind right now, at 30 feet, and is blocked by just 1 foot of stone, dirt or wood or 1 inch of metal. Probing deeper forces a DC 12 Wisdom save and tells the target someone is in its head.
• •It can change face mid-chase. As a bonus action, a 2024 doppelganger can turn a corner, become someone else and keep running in the same turn.

How the Doppelganger Fights

A doppelganger's real fight happens before initiative. It replaces someone, listens, and picks the moment. Combat is the last step, and it should start when the doppelganger chooses.

The 2014 opener. SRD 5.1 has the DM determine who might be surprised: if nobody is being stealthy, both sides notice each other; otherwise Stealth is compared to passive Perception, and anyone who "doesn't notice a threat" is surprised. A disguise isn't a Stealth check, so whether a trusted "ally" counts as an unnoticed threat is your ruling; the SRD doesn't settle it. If you rule that it does, the doppelganger gets Advantage plus Surprise Attack against that character. The math against AC 15:

The trait doesn't say "once". Read strictly, both Slams can add 3d6, for about 29 expected damage in round 1, more than a level 3 wizard's hit points. If that's too swingy for your table, apply Surprise Attack to the first hit only: about 21 expected. After round 1 the 2014 doppelganger drops to about 8 damage a round, so it should either finish its target fast or leave.

The 2024 opener. Two Slams with Advantage average about 18 damage against AC 15, and Multiattack also triggers Unsettling Visage, which is available at the start of the fight. Everyone within 15 feet who can see it makes a DC 12 Wisdom save. A cleric with +5 fails 30% of the time; a fighter with +0 fails 55% of the time. A frightened character has Disadvantage on attack rolls and ability checks while the doppelganger is in sight and can't move closer to it. From round 2 the 2024 version still deals about 13 a round.

Reading the party. In 2014, Read Thoughts gives Advantage on Deception, so a +6 liar rolling twice beats a +3 Insight check most of the time. Use the read to answer the party's questions. When someone asks the impostor "what did we eat on the road?", the answer is in the asker's surface thoughts.

Leaving. At 52 hit points with no resistances, a doppelganger loses a stand-up fight against a level 4 party. When it drops under half, it breaks line of sight and becomes someone else. In 2014 that costs its action; in 2024 it's a bonus action and it can still Dash.

Running a Doppelganger Encounter

A doppelganger is 700 XP. With the 2024 XP budget per character (SRD 5.2.1), for four characters:

Under the 2014 Dungeon Master's Guide guidelines (which our encounter calculator uses), one doppelganger is a Medium fight for four level 3 characters. The calculator can't see Surprise Attack. If the doppelganger gets its ambush on a trusting party, treat it as Hard.

Spread the encounter across a session. The best doppelganger scenes have a social phase (questions, alibis, a Detect Thoughts attempt), a reveal, and a short, violent fight. Use the NPC generator to build the person it replaced, so the party has a baseline to compare against.

How Players Beat a Doppelganger

• •Charm does nothing. It is immune to Charmed. Charm Person and Hold Person also target Humanoids only, and the doppelganger stays a Monstrosity in any form. Decide before the session what the caster notices when one of those spells has no valid target: if your table rules that the caster learns the spell failed, it's a strong clue.
• •Detect Evil and Good won't find it. That spell senses aberrations, celestials, elementals, fey, fiends and undead, not Monstrosities.
• •Ask questions the asker can't answer. A mind reader sees the expected answer in the questioner's head. Ask about something only the real person knows and check it later, or have someone the impostor can't read do the asking: farther than 60 feet away in 2014, 30 feet in 2024, or behind a wall.
• •Check the gear. Its equipment doesn't transform. Real items are missing from somewhere.
• •Read it back. The doppelganger knows Common (plus three more languages in 2024), so player-cast Detect Thoughts works on it. Its Wisdom save is only +1.
• •Spread out in 2024. Unsettling Visage only reaches 15 feet. A party standing in a tight knot around the "informant" all roll against it.
• •Hit it hard once it's revealed. AC 14 and 52 hit points with no resistances. It wants to leave, so block the door, ready attacks for when it moves, and keep someone on whoever it was last.

Doppelganger Encounter Ideas

The quartermaster. A caravan's supplies run short every third day, and the guard rotation keeps changing. The quartermaster has been a doppelganger since the river crossing, and the real one is tied up in a barge cabin two days back. The impostor is skimming supplies to sell to bandits who will hit the caravan at the pass. The party can catch it with an inventory check: its ledger handwriting changed on the day of the crossing.

Two mayors. The party returns to town and the mayor greets them in the square. An hour later, the mayor greets them again at the hall, with no memory of the first conversation. Both are convincing. One is real. The impostor read the party's minds during the first meeting and knows what they told the mayor last week; the real mayor, oddly, doesn't remember part of it, because the doppelganger has been meeting people in her place for a month.

The borrowed face. Merchants in the next city say a member of the party bought rope and lamp oil on credit yesterday, in that character's name. The doppelganger saw the character at an inn three days ago. It is building a reputation in that face, and the debt collectors arrive first.

Frequently Asked Questions

What CR is a doppelganger in 5e?

A doppelganger is CR 3 and worth 700 XP in both the 2014 and 2024 rules. It has AC 14, 52 hit points and two Slam attacks per turn.

Can a doppelganger read minds?

Yes. The 2014 doppelganger reads the surface thoughts of one creature within 60 feet with no saving throw and gains Advantage on Insight and Charisma checks against it. The 2024 doppelganger casts Detect Thoughts (save DC 12) instead, with the spell's 30-foot range.

Is a doppelganger immune to charm?

Yes. Both editions give it immunity to the Charmed condition. Spells like Charm Person and Hold Person also fail because they only target Humanoids, and a doppelganger is a Monstrosity even while disguised.

How does a doppelganger's surprise attack work?

In the 2014 rules, Ambusher gives it Advantage against any creature it surprised during the first round, and Surprise Attack adds 10 (3d6) damage when it hits that creature in the first round. The 2024 doppelganger drops both traits and instead has Advantage on its Slams in the first round of every combat.

Can a doppelganger turn into a specific person?

In the 2014 rules it can become a Small or Medium humanoid it has seen. The 2024 Shape-Shift lets it become any Medium or Small Humanoid, with no requirement to have seen it. In both editions its gear doesn't change. The 2014 version reverts to its true form when it dies; the 2024 text doesn't say. Loreify can record your sessions and keep track of who the party met, which helps when players need to remember what the "real" NPC said last month: see the D&D note-taking app.

Stat blocks: System Reference Document 5.1 (2014) and 5.2.1 (2024), Wizards of the Coast, CC-BY-4.0. Tactics, encounter math and ideas are Loreify's own.