It was previously located at the Spire until it is taken by Cassandra, who later uses it to control the remaining three members of the Brotherhood- Hector, Adira and Quirin. King Edmund was secretly under the mind control of the mind trap and he is also member of the Brotherhood. King Edmund destroyed it when Eugene speaks to his father.
It takes on the appearance of a stone with the Brotherhood symbol on it (a circle with three slashes), which turns white when activated.
In Race to the Spire is revealed that the Mind Trap is what Cassandra is after, to give herself "soldiers" in her war against Princess Rapunzel and all of Corona. It was revealed by Calliope that she kept the artifact in a box only she could open with a special key. A while later, Cassandra uses it to control the Brotherhood.
In Once a Handmaiden..., Cassandra brings out the Mind-Trap to summon Adira and Hector to prevent the citizens of Corona from entering the castle.
The Mind-Trap is shown to be at the throne room at Cassandra's Stronghold in Plus Est En Vous and Eugene tried to take
- It is the only object known to have the ability of controlling minds.
- It only controls those who have sworn loyalty to the Moonstone Opal.
About the Mind Trap
- "Tell me, where is the Mind-Trap?"
- "You mean the talisman that can control the minds of any who've sworn loyalty to the Moonstone, like the Brotherhood?"
- "It's safety locked up in a chest and can only be opened with a key that I possess."
- "It's no use, I can't get to the Mind Trap talisman!"
- "Cassandra, the Brotherhood of the Dark Kingdom is now yours to command."
- "They must be under the power of the Mind-Trap."
- "Yeah, but we'd have to know where Cassandra's hidden the Mind Trap."