How do GWFs and SA stack by RAW? I mean, what is the mechanics behind it? Do you get 2 effective re-rolls (under right conditions)?
Say you roll a d12. If you roll a 1 or 2, GWF comes into play and you re-roll it (we'll call this result A). Then you can use SA to roll all the damage again. If that rolls is a 1 or 2, you re-roll it again (which will be result B). Then you choose whether you take result A or result B.
Here are some example arrays of possible rolls: Case A (1, 4; 2, 11); Case B (2, 5; 2, 1); Case C (4; 12)
In Case A, you first roll a 1. GWF comes into play and you roll again, getting a 4.
Then you choose to use SA to re-roll.
The new roll results in a 2. GWF comes into play again and you get an 11.
Now, because of SA, you can choose either the 4 or the 11.
In Case B, you first roll a 2. GWF comes into play and you roll again, getting a 5.
Then you choose to use SA to re-roll.
The new roll results in a 2. GWF comes into play again and you get an 1.
Now, because of SA, you can choose either the 5 or the 1.
In Case C, you first roll a 4. GWF does not come into play.
Then you choose to use SA to re-roll.
The new roll results in a 12. GWF does not come into play.
Now, because of SA, you can choose either the 4 or the 12.
Of course, there are a lot more possible outcomes (20736 to be specific), but that should give you a better idea of how it would work at a table.
Sorry if I went a little overboard on the explanation; once a teacher, always a teacher, I suppose.
