The Wishing Well is a naturally-spawning structure exclusive to the Hamlet DLC that can be found in some rooms of the Ancient Pig Ruins.
Players can give treasures to the Wishing Well, in exchange for a chance for getting healed and curing Poison. The amount of health healed is equal to 125% of its percentage chance for successfully triggering the healing. For example, a Gold Nugget has an 80% chance to trigger healing, and will heal 100 when the effect occurs.
The End's Well can be found in a room of the Ancient Pig Ruins containing the Aporkalypse Calendar on the 5th island. It gives off a bassy, ambient humming sound effect and the water appears black.
The End's Well accepts Nightmare Fuel, spitting out either 1 or 3 Purple Gems. Other colored gems have a slight chance to cause the Well to spit out a Purple Gem. Giving any other item will result in a Shadow Creature spawning. This allows the player to turn a basic item into Nightmare Fuel, and Nightmare Fuel into an unending source of Purple Gems.