The VOIDRUNNER'S CODEX is coming! Explore new worlds, fight oppressive empires, fend off fearsome aliens, and wield deadly psionics with this comprehensive boxed set expansion for 5E and A5E!
It sounds like you're trying to 'dick over said player' without being caught 'dicking over said player'. You could always use common sense with you hostile npc's. If they come across a tank, take out its support (other PC's).
Have a good concept, and find an awesome picture to base them off. Stats and mechanics mean little compared to an awesome back story.
You roll better when you can visualise your character. But for the mechanics, see the guide: Meditation Meditation Devastation A monks guide