Permadeath Mode is a toggleable option when creating a new save file in Cadence of Hyrule.
Permadeath Mode is a game mode that makes it so that when the player experiences a Game Over, they will have to restart the game from the beginning or start a completely new save file. Toggling it also increases the game's difficulty, with stronger enemies appearing throughout Kingdom of Hyrule and dungeons now sporting two minibosses within their respective lobbies.
The four elemental bosses appear as their stronger red-and-blue counterparts regardless of the order of dungeons completed, and also gain the addition of Sarcophagi to their battlefields, which spawn undead enemies to attack the player during battle. The only bosses to not have Sarcophagi in their boss fights are Bass Guitarmos Knight and Octavo.
Toggling it also adds further randomization to a save file by randomizing the placement of key items, including those given out by sleeping characters, which can be found either by opening Treasure Chests, by mini-bosses, or have them given out by a different character entirely. The only exceptions to this rule are the Goron Locket, Snorkel, Tingle's Dowser, Bottles.
Additionally, the pricing of items are also doubled at all shops, including potions sold by the Fates and Weapon upgrades sold by the Great Fairies. Wearing the Ring of Charisma inside a shop temporarily returns the prices to their original state, but only as long as the ring is equipped.