For easy tame make a 1x1 about 4 high with metal walls and 1 metal foundation. Make the bottom 1x1 using metal door frames and a door on each. use wyvern to pick one up and drop it on top it's take a bit of practise but eventually the mantis will fall to bottom. Apply big repellant and have full gillie on. You can feed the horns through the door. Its might even work with normal walls at bottom never tried it. Also you could try adding ramps on all 4 sides from top to bottom sometimes you can kite it up into middle. This is by far safest way to do it without anything else bothering you.