Tarot Dungeon
A dungeon under Novgorod built by Igwolf.
Accessible only by pulling a Tarot card from a deck. Tarot card drawn will determine permanent changes to a person that may be good or ill. These changes can only be reversed if the Fool card is drawn - ripping a Tarot card together with the Fool card will reverse the effects. (Nicolae had a Fool card that was able to reverse the effects of four cards.) Ripping one's Tarot card while in the dungeon will transport one back out. Once someone leaves the dungeon, they can never enter it again unless they have magical Gloves of Readmittance.
One cannot sleep while in it because one will go mad.
Sadko visited it when he was young. He also knows the Tarot Dungeon Poem.
Vasli also went into the dungeon.
The Byzantine Envoys hacked the dungeon to get the the cave where beseigers were using a polluted pool to create their zombie army and successfully purified the pool, resulting in the end of the zombie army and the salvation of Novgorod.