Halo 3:
Flipyap - Listen to the tale of a young Grunt named Flipyap.
Who needs them? - On The Ark, complete the level without entering a vehicle on Legendary.
Mind the gap - 4 vehicles, 1 gap on Legendary using Cowbell, Catch, Thunderstorm, Mythic, and Tough Luck.
Annual - Complete Halo on 4-player Legendary co-op, with Iron Skull, and everyone in Ghosts.
Halo 4:
This is my rifle, this is my gun - Carry a UNSC weapon all the way through Forerunner on Heroic or Legendary.
Bros to the close - Complete Infinity without one preventable Marine death on Heroic or Legendary.
If you also need them or just want to join and help out, then add and message Dan Oney.