Qi Men Dun Jia is a multi-dimensional analysis of qi. Among the many dimensions, the Three Wonders Six Emblems(San Qi 三奇 Liu Yi 六儀) and Eight Doors (Ba Men 八門) are most important. This is why Qi 奇 and Men 門 become part of the name of the study.
Dun Jia 遁甲 is to make the leader invisible to give command from behind the scene.
In strategic planning, the technique of QMDJ is most rewarding. In the old days, it was used in warfares. Today, most people are going to the battle field everyday. In order to be the winner in the broad sense, the knowledge of QMDJ can be most helpful.
Having said that, I do not want to mislead the reader by exaggerating the power of QMDJ. Whether or not one can win in the battle field depends largely on other more important factors than QMDJ technique. Without good weapons one is sure to lose the war.