Ported from other version and also added code to disable it. Activate one at a time since they all patch same addresses. You can get over max damage when you abuse high multiplier with very powerfull weapons vs weak monsters in which case you'll actually deal very little dmg, remember that.
Maybe try to not abuse it, as the game doesn't really have much to do when you get through stuff too fast, I used this code mostly in MH1&2 when playing online stages offline to deal with boss hp multiplier. When you're against normal single player boss even x2 will make a huge difference(unfortunately because of how the code works, it's not possible to do smaller multiplier like x1.5 or something).