In my games, I encourage players to use their stress, their damage, to their benefit. I tell them that if they act cowardly, and primal or give in to the spiritual hitchhiker in their soul, they get more dice. Thus they are likely to pass their tests.

If players do what they're best at they will usually roll 3 dice. This is often enough to get through a difficulty 4 or 5 checks (87.5% and 70.5% respectively.) For a difficulty 6 test, however, it is only 42.1%. When doing what they're best at, they are still likely to fail at the highest difficulty.

If their stress is at 4 though, something happens. That difficulty 6 test gets odds of 51.8% if they use it. Crossing the threshold of likeliness. And it only goes up from there as you keep getting more and more stressed. 

Power and success are at the cost of morals, pride, and reputation. I offer it but it is the player who must decide the nature of their character. Will they give in? Or will they be steadfast and persevere? I like the idea that being dark and evil-ish are easy ways to be powerful but they are stressful. Never at ease. Never peaceful.