Taking a page from the new Star Wars RPG, I'm toying around with the idea of doing away with the A/C/E mechanic and replacing it with a Warhammer version of the Light Side/Dark Side points mechanic.
If would work like this.
Important NPCs/Baddies, would get their own Fortune Point pool, plus Talents/Actions.
All other NPCs/Baddies would draw from the GMs Chaos Point pool.
Chaos Points are generated at the beginning of the session by rolling 1 Misfortune Die for each PC. Any Banes generated are tallied and noted (with pen/paper or tokens). This is the GMs starting Chaos Point pool.
Whenever a PC spends a Fortune Point, the GM gets to add a Chaos Point to his pool.
Chaos Points can be spent in the following ways:
1 Chaos Point = 1 Fortune Die (added to the GMs dice pool), or 1 Misfortune dice (inflicted upon a PCs dice pool)
3 Chaos Points = 1 Expertise Die (added to the GMs dice pool), or 2 Misfortune dice (inflicted upon a PCs dice pool)
5 Chaos Points = 1 Challenge Die (added to a PCs dice pool)
I honestly haven't had a chance to play test this yet, so I'm not sure how balanced it will be compared to A/C/E