I'm guessing that, because you're asking about the trick with a set in front of it, that you can hit merlin. and, if you're a toe-to-toe player, you probably have a pixie set. So practice getting that pixie set to peak right above your belly button, and practice a downtime merlin that you attack right as the bag is peaking, then put the two together. make sure to put all your weight on the leg that is doing the 3rd dex so you can spring off it right after the 2nd dex. and don't the your merlin!
It is important to start Miraging dex as soon as possible. High Pixie set is not necesary. Fast Pixie set will help. And maybe try at first some Pixie ss Reverse Flails to be sure the last dex is clean.