I had that exact MF in my tank once. Hitchiker on Florida LR. There are two basic variations Smasher & Piercer. The one you got is a smasher. Dont get your hands near that MF cause the little bastard will knock you. Most people think that a tiny thing like that cant possibly cause pain but believe me man that s@#t hurts like hell.
Try to find out where that little sucker burrows, lift out that rock and do a fresh water dip. Traps and things take too long and those suckers are smart man.
The best advice I can give you is take out all of your other livestock especially shrimp and small fish as they will dissapear very quickly. The mantis is a highly efficient predator.
If and when you get him out make like a 10g nano for. Awsome animal when there is nothing to kill. And most of all keep the sucker well fed so he wont be hungry for your cleaners man. Any raw fish will do. The one I had really liked salmon.
I really hope you get this dude out of your main tank. Good luck to your fingers!!