Was just reading Imperial Armor Apocalypse 2nd Ed (the one with the Contemptor Class Dreds), and on p. 67 it lists an Eldar Apoc Formation called "Guardian Serpent Rider Host" -- and notes that one of the unit benefits is called Shadowfire.
While the formation command vehicle remains mobile, the entire formation benefits from the Night Vision/Acute Senses rule and may reroll failed Target Priority tests.
So first, I'd note that it says Night vision checks, not Night Fighting.
And second, does this portend Target Priority Tests coming back a la 4th ed?