Before a complex system is deployed, it is tested -- but it is tested against known operational mission, under several known operational scenarios. Once the system is deployed, new possible unexpected and/or uncertain operational scenarios emerge. It is desirable to develop methodologies to test the system against such scenarios. A possible methodology to test the system would be to generate the worst case scenario that we can think of -- to understand, in principle, the behavior of the system. So, we face a question of generating such worst-case scenarios. In this paper, we provide some guidance on how to generate such worst-case scenarios.