Ethereum Prison Key

Ethereum Prison Keys are keys used to open an Ethereum Prison.

Prerequisites
For the Ethereum Prison Keys to drop or allow one to roll on them within a party, one has to be honored with the Consortium and has to have completed the quest.

If those prerequisites are not met the Ethereum Prison Key will not drop nor can one roll on them when they drop while within a party.

Source
Once the prerequisites are met, the Ethereum Prison Key drops off:
 * Ethereum mobs in the Arcatraz
 * Ethereal mobs in the Mana-Tombs
 * Ethereum mobs around Manaforge Ultris
 * Zaxxis mobs in and around The Heap
 * Bash'ir mobs in Bash'ir Landing

Note that the Ethereum Jailor around Manaforge Ultris in particular has a 100% drop rate of the Ethereum Prison Key.

As of Patch 2.3 a Ethereum Prison Key can be obtained by completing the (Non-Heroic) Daily Dungeon Quest given by Nether-Stalker Mah'duun. The key is rewarded regardless of the above mentioned prerequisites.