[1.2.291] [KOR] Dual Blade Skill Tables

Anyone found a video of a dual blader using stack skill? i am really interested to see if they sacrifice sp for its use.. I was thinking they just make a 3rd image of themselves as a puppet.. losing sp for its use would suck as well as start to be costy, using rocks to re use sp after you use stack.. unless using sp after stack cancels the stack which would also suck lol..