Dark Elixir is yet another resource to be collected. So why is it here? It is because Clash of New happened. And the Barbarian King.
Originally it was impossible to find as it was hidden deep down in the lava realm. Then some Barbarians discovered Dark Elixir and one of them accdently summoned a Barbarian King. The discovery of Dark Elixir caused a funky drill called the Dark Elixir Drill to be invented.