Dionesium is a naturally occurring liquid metal that has the supernatural ability to revive dead tissue, bringing those who encounter it back to life.
Dionesium was named by its researcher and discoverer Paul Dekker after Dionysus, the Greek god of rebirth. Natural, uncorrupted Dionesium is hard to come by, often found mixed with other materials, such as the rock that gave Vandal Savage his powers, Lazarus Pits, which are usually controlled by Ra's al Ghul, or mixed in with the Court of Owls' Electrum alloy.
However, by chance, the Joker accidentally fell into a concentrated pit of Dionesium hidden beneath Gotham after one of his schemes against Batman. The Dionesium not only healed his severed face-skin but affected his blood so much that he gained a limited amount of revival powers that he used in his endgame against Batman. The concentrated pool that Joker fell into was seemingly destroyed following his final confrontation with Batman. However, both the hero and villain still made enough contact with the element to revive them from death, albeit with their memories temporarily gone.
Dionesium was one of the five metals that, when all touched to a single person, could create a portal to the Dark Multiverse. Unknown to Batman, he was cast to be the portal and was purposefully exposed to Dionesium in his fight with the Joker.
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