I could only see one issue with the kill 50 or w/e times idea with NMs. Some times you need mages, although that could be fixed by adding some type of extra item that lets them buy a helm or w/e the trophy from the NM is and then trade it with the weapon to the box, this could easily be done by having a line saying if no trial target number down key item currency goes up or something while trial number x is active. Might not be the easiest to code but it'd be the smartest deployment, but you know omg its easy mode because it encourages team work and does not inspire people to pick up ethnic slurs to curse people out in three to five languages.