Lazarus Pit (Earth-18)

The Lazarus Pit is a pool of regenerative waters that allowed the user to heal themselves of any wounds, or even prevent aging to a certain extent.

History
On December 10, 2019, following Oliver Queen's death, John Constantine discovered the Pit, while searching for an Earth with a functioning one. It was watched over by Jonah Hex's Earth-18 doppelgänger. They bathed Oliver in it, bringing him back to life.