This stage is only available in the History version of Cave of Sealed Time. In order to move around inside the dungeon itself, you will need a Dungeon Key dropped by the skeletons in History 2-9 and 2-10. At this time, this stage's main purpose is for level 45+ characters to obtain the confirmed stone tablet required to access Kanhel's Ruins, although there are low level monsters and quests available.
This stage is available in both the History and Legend version of Cave of Sealed Time. In this stage, you will search 16 rooms populated with enemies from the last half of Episode 2 for a miniboss, who is randomly either an Evil Eye's Master or Blade Claw Lord. This miniboss will drop a single treasure box that the entire party will have to share. Usually there will be a minor accessory in the box, but you can also get an extremely rare ring with good stats. Also, because this stage is basically nothing but constant fighting, you can earn decent experience here.
This stage is only available in the Legend version of Cave of Sealed Time. In order to pass the door, you will need a confirmed stone tablet as well as a Ghost's Key. This is an 8 man stage in which you hunt down a massive dragon named Kanhel. You must be over level 45 in order to get Ghost's Keys to participate in this stage.