You need special items to enter the event location during an Event. You can get them:
- by exploring locations and playing mini-games,
- from event monsters and in their treasuries,
- as a reward for the Phantom Hunt and Gemstone Vault mini-events,
- in a daily chest from the Curiosity Shop and from event totems,
- by buying them with rubies in the Event section of the Store and with real money as part of hot deals.