servant of darkness

Ok first of all crouch right away then slowly open the door thats in front of you or on the left and go up the stairs quietly you will hear a guard walking around on the top.

Get your thermal vision out and when you think he has left (you will hear him open and close the door) check as quietly as possible you will be able to see him through the door.

Carefully go towards the door and open the door only when he enters another room and quickly but quietly go across the room and open the door and go outside now still in crouch stance go to the ladderand wait for the gaurd at hte bottom to be facing away from you then climb down.

Go the way the gaurd went and stay behind him he'll turn again now just wait untill you think he's going in the direction where the ladder is, go ahead to the van with the open trunk and place the bomb.

Now thats over you can be as trigger happy as you want but it sure doesn't get easier.(the gaurds have a super sense of hearing so don't make noise you might need to try a few times).