What is the rarest key of tibia?

Question

There are many keys in the game but I would like to know which is the rarest or difficult to obtain

Answer 1

The rarest key of all would have to have been Key 0000. Originally wooden, then changed to purple. Was created by CIP to access all rooms, once was obtained by a player (wasn't supposed to happen) and quickly deactiviated once CIP realised what had happened. Owner was eventually hacked and lost all their keys, though eventually the key was bought to keep it as this part of Tibian history