Talk:Exterminate/@comment-27288869-20160521010720/@comment-195.211.79.82-20160521105926

Oh, it was easier to find than I thought,

https://forums.warframe.com/topic/618642-update-185-sands-of-inaros- / But it says timer doesn't work when all enemies are killed, maybe it was changed since then one more time.
 * Exterminate Missions now require a players to earn a kill every 15 minutes.  A 20 second warning will be given before the end of the 15 minute period, at which point players that have not killed an enemy will automatically fail the Mission.  *Please note: This timer is cancelled when an Exterminate Objective has been completed, allowing players to roam a level for as long as they like!