The Mansion Key is a monster drop that can be found in the Nightmare. It can be found from various sources and locations throughout the Nightmare including but not limited to:
- A rare drop from a Red Wolf.
- A very rare drop from a Mansion Ant.
- A very rare drop from a Nightmare Lantern.
- Being rewarded from the Ratfolk in the graveyard at Topple Town.
In appearance, the Mansion Key is a key made out of hardened bronze and gold. The Mansion Key is mainly used to unlock doors sealed with the keylocks that can only be opened by the Mansion Key. If the player has no purpose for the Mansion Key, it can be sold for 0 gold.
- The Mansion Key will not drop on death and can be obtained from the Pig should it be lost or dropped.