When you attack / Intel reach a certain point it does seriously effect the troops it attacks. (evidence in guides in the guide section)

You would have to look up a guide of 0spawn0's or satan's for more information as i personally still dont fully understand the Intel part yet.

But attack does effect this for certain, and im sure Intel does also.

Try looking over there in the guide section mate, may help you understand a bit more, but there is a lot of reading through the threads on hc attacks before you will find what your looking for.