Its when you dodge an attack sent at you and then time a counter attack to reach your attackers village within a second (preferably) of his offense troops returning home.
So that he cannot dodge and loses ALL his offense.
The most fundamental theory of Cancel Sniping is that any attack you send out, when cancelled, will return to the home village at the exact milli-second that the attack would have hit it's destination.
So the trick with Cancel Sniping is to attack a barb from your
defending village, so that the attack would land with the correct ms that lie between your noble train. You then work out the precise time you need to cancel that attack so that it takes the troops the same amount of seconds to return home as it does for your noble train to hit. The milliseconds part is taken care of already.
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