Like any normal server, Elysium has a Nether. It can be accessed via any obsidian portal. For more information about general Minecraft mechanics of the Nether, please refer to the official Minecraft wiki article: http://minecraft.gamepedia.com/The_Nether
In Elysium, the Nether is reset on a monthly basis (usually on the first Saturday of each month between 1 to 4pm EST). This process is executed in the form of a public event hosted in the End, which is also reset at the same time. The monthly reset event always includes the slaying of the Ancient Dragon and other support mobs, like Fire Elementals, to slow down the destruction.
Once the reset is complete, all items and buildings in the Nether are renewed to their naturally generated form. This also means that the items inside nether fortresses are also renewed on a monthly basis.
WARNING: After a reset, do not enter the Nether/End until the staff member managing the reset has informed you it is safe to enter, otherwise you may lose items or have other issues occur.
In addition to the material value of items to be plundered in the Nether, many players of Elysium also venture there to make money. Most monsters in the Nether have higher monetary rewards for being killed, which makes the Nether a very profitable place to venture (if the player has sufficient tools/armour and weapons to take on the Nether).
Just like in the Elysium Overworld, all items are kept if a player dies in the Nether.