Not sure if this was a bug or what.
There I am minding my own business, doing a cetus wisp run at night. I got to twin horns and there was a revanent (like from the mission) blasting away at some grineer. I was in my limbo rift so I walked up to look at him and sure enough his name said Revanent. He killed me in 2 shots so he seems stronger than the one in the mission. I got sent back to my orbited when I died the last time .
Was this a bug or do we need to keep an eye out for random ghost revanent warframe on the plains of eidolon from now on.
It wasn't bad just unexpected.