How to check for invisible attacks

How to check for invisible attacks :

Helps to avoid trap in outer domains, salt lakes, grails, etc, and save your troops from being wiped off. :)

It is done by joining your own, ally, or clanmate's attack, and comparing visionary report with what you see in missions launch window:

• launch attack

It doesn't have to be robbery attack like on screenshot, any type would do.

• vision and make a note of ongoing attacks (in this case there is mine only)

• then try joining, and pay attention to the number in parentheses next to nickname in a drop down menu, it shows a total number of attacks besides the one you are joining.

    As you see on the screenshot below, there is no number next to nickname. It  means that I'm the only one attacking at the moment, just like visionary report showed, and there is nothing to worry about.

    According to this screenshot  there is someone else attacking the same domain. And if I can't see this attack in visionary report, means player is using invisibility spell. 

    If it was a grail or lake seizure, I could have gotten into a trap, when invisible player with strong army seizes right before me, and all my troops die upon arriving.