Absorbing the Aboleth matriarch's eye has granted the owner the ability to read one's thoughts.

The creature who absorbed the eye is now proficient in Insight and once a day can attempt read a creatures thoughts that they are within 30 ft of.  The owner must pass a Insight DC 14 check and you must be able to see the creature you are trying to read.  On a successful roll you can learn either what the creatures intentions are in the current situation or what their greatest desire is.  On a failed roll you cannot attempt to read the creature's thoughts ever again.