The Wishing Well is naturally-spawning structure exclusive to the Hamlet DLC that can be found in Ruinous Caves.
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 a 80% chance to trigger healing, and will heal 100 when the effect occurs.
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 Nightmare Creature spawning. This allows the player to turn a basic item into Nightmare Fuel, and Nightmare Fuel into an unending source of easy Purple Gems.