Undead Telepathy resist

When a Doppelganger impersonated someone, it was more difficult for people
closer to the target to see through their disguise. That was because they used a
form of telepathy during their shapeshifting to read the surface thoughts of the
people they were speaking to and those around them in order to extract
information related to the target they were impersonating and then apply it to
their impersonation act ― at least, that was what their entry in the monster
encyclopedia said.
According to Pandora’s Actor, that ability had become real in this world.
However, that was simply to discern the possible reactions that the
impersonated subject might have, and it did not read minds or search through
memories.
In addition, since this ability was a form of psychic attack, it was useless on
Ainz and other undead creatures.

- Overlord; Vol 13; Chapter 5