Dead men Tell No Tales

You target yourself and up to 8 willing creatures during the casting of this spell, and speak of an event, piece of information or secret. If after this spell is cast a targeted creature attempts in any way to divulge the spoken information to anyone not involved in the initial casting of the spell, they must make a constitution saving throw against your spell save DC. On a fail, the creature immediately dies before it can share the information. When killed in this way the creature cannot be targeted by the speak with dead spell and if brought back to life by a spell, other than a wish spell, they return having forgotten the relevant information.  On a success the creature takes 75 psychic damage, and is cursed with a black spot. While cursed in this way all creatures subject to the original casting know the creatures exact location at all times while on the same plane of existence.