I think he meant to say he doesn't know what codex (or player) he is going to play against when he makes the list and packs he's models.
New Dark Eldar in Tournaments: Wins: 17 Draws: 2 Losses: 8
ETC 2013 DE/Eldar player (4th)
ETC 2014 Coach (16th)
ETC 2015 Captain, Eldar/DE (10th)Painting blog