How To Unlock Secret Boss In Deltarune Chapter 5—Where To Use Mystery Key
Deltarune Chapter 5 has been released and features a secret boss accessible through a hidden encounter. To unlock the secret boss, players must obtain the Mystery Key, which is a purchasable item available within the game. Beyond acquiring the key itself, players will need to gather rare collectables and navigate a specific route through the newly introduced Flower World area to locate the entrance to the secret battle. The guide indicates that while the Mystery Key can be acquired relatively straightforwardly through purchase, finding the actual boss location requires careful navigation and exploration, as it’s easy to get lost within the Flower World section of the chapter.