Just to complement to Hellgate's Solution.
Press
and Go to the Objetives Board and to the right you'll find the Faction Missions, search for the ones marked with a Skull/Knife, complete 5 of them and Achievement Unlocked.
A few things of interest:
- They reset each day at 03:00 am (UTC-06:00)
- Number avaliable per day is Random
- Replaying the same Faction mission doesn't count for the Achievement, you need to play 5 different ones.
- Both "Staying safe" and A Long Road to Victory" elite missions counts towards this.
Your objetives will be the regular faction mission ones, "Locate info", "Locate truck", etc. Just remember that you can save a lot of time if you get a "Destroy X" objetive and just blow it out with your helicopter, locations don't need to be cleaned out to finish the mission (Unless your objetive it's to clear a whole base)
.