The Mimic's Entry Ticket is a random reward from any of Dreamscape's PVM. The drop chance of receiving one is 1 / 3,000. It is used to access the Mimic boss fight. The ticket is a one-time use & is destroyed on use. The Tickets are automatically banked when received.
At the moment, the price of the Mimic's Entry Ticket is roughly: 3M-6M DScoins