Wraiths can be found at places of power.
They are weak against moon dust, specter oil, yrden and quen.
Wraiths are very dangerous in large groups, however their tendency to drift and wander aimlessly makes them relatively benign at a distance in most cases. This allows the opportunity to confront wraiths in relatively small groups. Wraiths are completely immune to the shock of Samum, though they can be stunned for brief periods using the sign of Axii. They are incredibly resilient to fire and high temperature extremes making Dancing Star and the sign of Igni largely ineffective, however more explosive concoctions such as Grapeshot can be quite useful.
Not quite as tricky as noonwraiths, wraiths can still be a pain, especially in groups. Wraiths hold a sword and a lantern, and use them to slash and smack their enemies. Most of their offensives are preceded by a stint of teleportation, but once you know the pattern, it's quite easy to avoid the incoming attacks.
The first time that they teleport is usually a bluff. They'll reappear quickly, and then vanish again. It's this second disappearance that's the one to watch, because the next time a wraith emerges, it'll be next to you, and it'll try and lash out with a small combo. The first attack can be blocked, but it'll stagger you slightly, leaving you open for the second hit. As such, you're best off rolling away as soon as they appear in your vicinity after that second round of telepotation. Once you've dodged that, a few good hits with your blade is usually enough to either kill or severely weaken the monster.