Lone Wolf

The hardest achievement in the game: every mission on Legendary entirely solo, no co-op revives. Do it last, once you know the encounters and where the power weapons and Prometheans spawn. Play patient - lean on cover, Smart-Link and precision kills, and don't be shy about reverting to the last checkpoint rather than burning through on a bad push. If you did Legendary in co-op for Forging a Legend first, you'll already know the routes.