[Renewal] How to do INSTANT COUNTER with RK?

[ThanatosIXII]

I see lot of videos with RKs doing INSTANT COUNTER + Crushing Strike on MVP and 1 hit killing bosses.
My Problem is... I cant find the correct time to use counter and attack to get the instant counter... I am on a privateserver practicing this but I was only able to do this like 2 times in hours....
Please, somebody make a good tutorial of how to get this Instant Counter... really need this...