Reverse E Kassadin ? (RIP with patch 7.10)

Hi guys, today i show you a tips on kassadin for "brain" your opponent.
It's pretty simple, if you were a user of the reverse ult's cassiopeia(RIP) , you will do it easily.
First press E in the direction of your opponent and after use flash on your back. You need to be fast or it'll fail. The damage will be in the zone where the E is launched, so that the opponent will not see this zone.
Enjoy :D.