The Santa’s Workshop Key open Santa’s Workshop dungeon.
Santa’s Workshop is an event dungeon was released for Oryxmas 2017. It is a solo dungeon and cannot be opened anywhere besides the owner’s vault.
This dungeon has no hazards and is a race against time to destroy as many loot-containing presents within 120 seconds. When one section of the dungeon is cleared, the next one will open up. The farther you get, the better the possible loot becomes. Once the timer is up, a Nexus Portal will appear in the middle of the dungeon and all remaining presents become invulnerable.