Piercing the shroud

So i finished all the missions of the campaign,it says 25/25 and on the achievements i see that there is a mission called "Piercing the shroud " that i have never played.it is on the rebellion missions..is it a bonus mission??how can i play it?should i unlock it somehow??
i can't take the Completionist achievements because i can't play this mission!
the missions are 29 and i have played all 28 of them but still can't find anywhere this last one...

Somebody help please

 

Destroy the Science facility in the mission "media blitz" i think.
somewhere where u can destroy a sci facility lol!

 

It should be somewhere near your base, and it is at the right corner of the map.

 

Thanks heaps guys ive been looking for this for ages..

 

I am pretty sure you also need to kill it and pick up the item that drops during the odins surprise.

 

re:

+1

 

Yes, As you destroy the Science Facility, there will be a breifcase with secreat documents.. you must walk over it to activate the special objective. Once completing this you gain access to a new level, "Piercing the shrould".

"Piercing the shrould" is a zerg hybrid space station, your mission is to send in a small tactical unit and infiltrate and destroy the Dominions plans to create Hybrid monsters.

This facility is full of power ups / special weapons / and Crazy Hybrid monsters seen at the end of the SC2 campagin..