You can enter the Aspen Dungeon from level 72. It is found ideal alongside the Arena building. It opens once every 4 days, goes on for 48 hours.
You can send 5 Heroes altogether to the Dungeon and attempt to get into it as profound as you can by battling diverse methods for beasts.
After every 100 waves, you enter another dimension of the Dungeon with a lot more grounded beasts.
Right now, there are 5 levels altogether: Easy; Normal; Difficult; Nightmare and Hell.
After every 50 waves, you achieve another achievement. By that way, from the following Aspen Dungeon occasion, you will begin the diversion from that achievement.