http://us.battle.net/sc2/en/blog/2356436
"Liberty Completionist Hard" and "Liberty Completionist Brutal" achievements are now the final achievements in the "Wings Of Liberty: Hard" and "Wings Of Liberty: Brutal" series.
Can't understand what does that mean? Could you please explain?
Best Answer
Currently, the achievements called "Wings Of Liberty: Hard" and "Wings Of Liberty: Brutal" simply count the number of missions you have completed at each difficulty and give you an achievement for every 5 missions you have completed. So, you get a level of the achievement at 5, 10, 15, 20, and 25 missions completed. Right now, they both give you the final tier of the achievement once you complete 25 missions at that difficulty level.
Your quote is indicating that they are adding a final level above the "25 missions" reward. You also have to gain the "Liberty Completionist Hard" and "Liberty Completionist Brutal" achievements (which require you to have completed all 29 missions) before you get the final tier of the "Wings of Liberty" achievement for that difficulty.