Q: How do you counter stealthed NBs?
A: they can't stealth forever and can only damage you when they are not stealthed. So react quickly when they get out of hiding.

Q: how do you cleanse adverse statuses like reapers' mark, poison, dot, etc..
A: You can't cleanse dot's. you can counter it by buffs and direct healing.

Q: What does it mean when you hit someone and it says reflected?
A: most commonly this happens to projectiles. If reflected they missed the target.