Talk:Nightmare Mode/@comment-220.253.39.136-20150917112338/@comment-8256051-20150917114108

Because Oro is not technically an "earth level" mission. The highest level on Earth is 5-7 or 5-15 and the boss is 20-25 (and locked until MR5). Also, the same thing happens sometimes on Venus, Fossa becomes available in Nightmare.

There is only those two missions that escape the rule of "no nightmare on Earth, Mercury and Venus".