In DragonVale for the Android, iPhone, and iPad, the Electrum Dragon is an Epic hybrid dragon that you can breed at level 19.
The Electrum Dragon nets you 550k XP, sells for 4.5 million coins, and has a 47 hour and 30 minute base breeding time. The Electrum Dragon belongs in the Treasure habitat.
To breed an Electrum Dragon, you just need to breed dragons that contain the Lightning and Metal elements. Even the basic Lightning + Metal dragons can get you an Electrum Dragon, though the chance is still slim since it’s an Epic Dragon.