There are three ways to get Corrupted Eyes (the resource needed to enter the new Mystic Realm event):

1.  You can get 10 Corrupted Eyes once a day for free by logging into the game.
2. You can get 10 Corrupted Eyes once a day by watching an ad.
3. You can purchase 10 Corrupted Eyes for 100 orbs.

Please note that you will NOT get Corrupted Eyes by attacking other players' dungeons, as is the case with the other weekly events.