Corrupting a sister of battle.
What say the community?
It's a project my group is kind of working on right now actually.
And by my group, I mean one guy from the two-player (and one GM) game I'm in who isn't me. As opposed to my 6-man (and one GM) game.
That said, players will try to corrupt anything and it's not like the Sisters are immune; I believe there are storied examples of ones who have fallen to corruption.
So what I'm saying is that it's only impossible if you hold yourself back - the sky's the limit!