Just some examples. Mainly what I thought they could use for the campaign.
WAKE UP, BUTTERCUP: Complete the wake up procedure (Easy or Normal difficulty, and yes I know it was already used in Halo Reach)
DID WE LOSE THEM?: Beat The Pillar of Autumn
CRASH COURSE: Beat Halo
JAIL BREAKER: Beat Truth and Reconiliation
CAN WE MAKE ANYMORE NOISE?: Beat The Silent Cartographer
INCLEMENT WEATHER: Beat Assault on the Control Room
THE COMING FLOOD: Beat 343 Guilty Spark
HORROR/SURVIVAL SECTION: Beat The Library
THE TRU7TH…: Beat Two Betrayals
DEJA VU: Beat Keyes
HOMECOMING: Beat The Maw
JUST GETTING STARTED: Beat the game on any difficulty
DUST AND ECHOES: Beat the game on Heroic
YOU DESERVE A HUG: Beat the game on Legendary
TOO COOL FOR OLD SCHOOL: Beat the game 100% (All difficulties, all achievements, all terminals, etc.)
I want to give XStuffofLegendX credit as I did not know there was already a thoroughly made achievement thread before this