Use the Artifact no more than once in the “All In” mission on Hard difficulty.
Complete all 29 Wings of Liberty campaign missions on Brutal difficulty.
Complete all the Artifact mission achievements.
Complete the “Left 2 Die” scenario before the fifth night on Brutal difficulty.
Survive 15 Infested Horde Attacks in the “Night 2 Die" mode of the “Left 2 Die” scenario.