Warhammer 40,000: Dawn of War II

To get this you need to use the Chaos Sorcerer. Beyond that you can use Heretics and any unit that can be given the mark of Tzeentch, such as Chaos Space Marines and Havoc's. You can also use Dreadnoughts and Predators. You can not use Mark of Khorne or Nurgle upgrades or Plague Marines, Bloodletters, Blood Crushers or the Great Unclean one.

If you use a neutral unit, one without a mark and do not upgrade before the end of the game you will still get the achievement.