Critical Strikes and auto-confirmation

Question

Afternoon everyone. I have a query about a fighter build I am working on. So at lvl 20 a fighter gains the class ability Weapon Mastery that makes all critical threat automatically confirmed with one chosen weapon.

With the advanced feats you can apply a CMB based strike like bull rush strike (perform a bull rush if your confirmation roll exceeds your opponents CMD), tripping strike (perform a trip maneuver if your confirmation roll exceeds your opponents CMD), disarming strike (perform a disarm if your confirmation roll exceeds your opponents CMD)..

What I would like to know is how they interact. Does the fighter ability basically give me a nat 20 roll on confirmation and it applies the strike? Do I just roll confirmation for the strike effect and still confirm the crit no matter what I roll, or do I have risk missing the crit in order to apply the strike effect?

Edited: Also with Weapon Mastery, there is no may in whether or not you can take the auto-confirmation. So I don't think the 3rd option is even available.

Answer 1

The description for Weapon Mastery doesn't say to act as though you'd gotten a specific result. Essentially, it means that the result no longer has any effect on whether or not the hit is confirmed. Most of the time, there's no practical difference between these two: there's no reason to make a confirmation roll except to confirm a critical hit, so if you don't need a number for that anymore, then you can safely omit the roll entirely. And that's exactly what most people do, and most of the time, this is fine.

However, these feats create a case where the difference matters. You need a number to determine whether or not you can apply these feats, and Weapon Mastery doesn't give you a number. This means that it's no longer safe to omit the die roll: you'll still always confirm the crit because Weapon Mastery says so, but you need the number for something else.

In other words, your second option is correct. You need to start making confirmation rolls again, to determine whether or not you can apply the feat. But the critical hit itself is not at risk: that will happen even if the die comes up 1.