So, when the opposition is 2 purple dice and 2 setbacks what combination of yellows and greens would you all expect to have somewhere between a 50-75% success rate?

That's a pretty tough pool. The PC would have to be well trained or very naturally talented to have good odds of succeeding.

2 Proficiency (Yellow) and 1 Ability (Green) would have a 53% chance of at least one success.

4 Ability (Green) would have a 57% chance of at least one success.

4 Proficiency (Yellow) would have a 74% chance of at least one success.

A good rule of thumb is that if there are more negative dice than positive you're in real trouble, if there are more positive dice you're in pretty good shape, and if there are the same number you need to have better dice (i.e. yellow vs. purple).

4 hours ago, 2P51 said:

Intense chart sir.

That is an incredible chart. Cthulhu bless math nerds.

Don’t forget the incredible AnyDice page. You can change around your dice pool, the set it to show you ‘at least’ to find out the chance of success.