Destroyer of Nightmares

The Destroyer of Nightmares is the item that drops from the Final boss of Quod Aeterna Vicis. It completely marks the end of Nightmare Mode and closes the Black Hole. If used, the world will go into The Epilogue, same as the end of the War Mode. There is also a second opinion: If you actually trash / put it into the chest / throw the item into the lava, the "Superior Nightmare" item will appear in your inventory instead. This is the item to summon the Night-Night-Mare boss.