Orokin Void
The Orokin Void or Orokin Towers exist in small pocket dimensions that are outside the realms of normal space. These are what appear to be fully functional Orokin structures, but they are not unprotected. Each tower contains what is described as a Neural Sentry that controls the security measures of the tower. The tower uses implant devices on intruders to create enemies known as the Corrupted. These Corruptedcounterparts act very similar to their normal brethren, except they defend the tower until death. Getting to the Orokin towers requires a Void Key or an invite from a player with one. The keys are eitherSurvival, Capture, Defense, Mobile Defense or Exterminate and have 3 tiers of difficulty, the third tier having higher chances for the rarest drops. Raid void keys turned into Survival void keys as of update 10. One unique feature of the Orokin Void is that Prime Warframes will cause the box traps to emit a wave of energy that will grant 100 energy to all frames within 30 meters. This may only happen once per trap.
If a Tenno has a Void Key, they simply select the key they wish to use from their Key Menu next to the Mode Select (play mission) button at the top of their screen. You can only select this while you are not in the lobby. Once you select the key for the mission type you wish to perform, you can invite other players from either your clan, friends or through the /invite command to participate in the mission with you. Other Tenno cannot join you without invitation. Void Keys are only consumed upon successful completion of the Void Mission. Aborting, disconnecting, or otherwise failing a Void Mission will not consume the Key. However as with all mission varieties, all completion rewards, credits, blueprints, and materials are forfeit upon failing a Void Mission.
資料來源:http://warframe.wikia.com/wiki/Orokin_Void