This dungeon is not always available to be played in-game. It is only available sometimes. It is currently available.
"Devilmon Cave is an event-only dungeon."
The Devilmon Cave is a special event-only dungeon consisting of only Devilmon. There is one stage, which consists of a boss Devilmon. Defeating it will cause it to divide into two smaller ones, each of
which will divided once more when defeated for a possible total of four Devilmon.Clearing stage will award a player with a Devilmon. Once dungeon is cleared once, players may not enter the dungeon to clear it again.