Can you use prowess to re-roll a 1?
what is A1 ?? enemy token?
By 'a 1' he means a die roll with a value of 1
Main rule to remember is that Prowess works with Combat (6 sided) dice only.
...unless you're playing with "Tactics" expansion. Prowess works for a few of those checks too.
Covered in my unquoted "(unless stated otherwise by a card/script)"