Doppler

Dopplers, also called vexlings or changelings, can take the shape of any human, humanoid or animal they like. It’s no illusion that a simple spell could break. The change is real and complete, and a doppler even takes on the aura of the creature it copies, so a witcher’s medallion won’t give it away. The bestiary sorts them among the relicts.

Dopplers are very clever and cunning, but they are gentle and timid at heart and do almost anything to avoid bloodshed. That hasn’t kept them safe. In Novigrad they are hunted along with mages and other nonhumans.

The Witcher 3 opens its Novigrad chapter on that note. In Pyres of Novigrad a doppler is burned at the stake in Hierarch Square next to a sorceress. Geralt’s old acquaintance Dudu, whom he first met in the short story “The Eternal Fire”, turns out to have helped Ciri and Dandelion in Count Reuven’s Treasure and Ciri’s Story: Visiting Junior, and The Play’s the Thing needs an actor to play the doppler. Dopplers can also be monster targets. The thief in Contract: An Elusive Thief drops a doppler trophy and mutagen if you kill him.

Combat strategy

Most dopplers you meet are not hostile, and some quests let you settle things without a fight. In Contract: An Elusive Thief you can spare the culprit and still get paid. If a fight does happen, remember that the doppler fights in whatever form it has taken, so read the attacks of that form rather than expecting a monster’s moves.

Because a doppler’s disguise is a real change, your medallion is no help in spotting one. Clues, tracks and Witcher Senses do the work.

Apply Relict Oil to your sword if you plan to fight.
Use Witcher Senses to follow the trail, since magic detection won’t reveal a doppler.
Think before you strike. Sparing the doppler in An Elusive Thief earns coin and a diagram, while killing him gives a trophy and the doppler mutagen.
Treat its attacks like those of the form it wears, and dodge accordingly.