I found using every <CS> did not sit well with my players, every time they roll a task there is a minimum 1 in 8 of getting a <CS>, but I do want to use it to add flavor to the game. Using it whenever I feel like it is a bit unfair to the players so I came up with a simple system to determine how bad the effect is.

I hope you guys try this out and like it:

1. First spend all <CS> on regular in game effects (action, casting, unreliable, environment etc.)
2. Count remaining <CS> as bane & roll a purple die for every <CS> remaining, keep rolling purples if you get <CS> on them.
4. Count all skulls (bane) symbols as fumble level indicator (no on the original purple dies)

1xSkull a Minor mishap
2xSkulls a Fumble
3xSkulls Something bad
4xSkulls Something Horrible
5xSkulls Something brakes

This gives an easy task a little chance of fubling but harder are more likely to fumble and do so alot worse.

I plan on creating a small fumble table for meele, range, gunpowder, physical, mental and communication rolls but I have not had the time yet.

Reading over this I realize I am explaining this rather badly.

For every <CS> rolled that is not being used you roll a purple fumble roll.

Each roll will generate:
1-5 No effect
6 1skull to fumble
7 2skulls to fumble
8 1skull to fumble and an additional roll

So getting <CS> on your initial roll and then 2 skulls on your fumble roll would give the bane effect on your roll and “2 Fumble”

I found that most of the time, after resolving CS effects on cards, there's rarely some left. Also, miscast rules already have a use for "unspent" CS.

Beside this, rolling new dices for each unused CS slows the game too much for my liking. Much of the people rule out that CS count as 1 challenge and 1 bane. It's faster and there's already an effect for extra banes and challenges.

If you want to keep a feel for levels of fumbling, you could rule out that if you fail a check, if you have more than X challenges left (after putting appart challenges that canceled successes), you fumble. The more challenges left, the more dire the fumble effect.

Whaddya think ?

Here's what I do:

GM’s Suggested Effects for Unresolved Star or Comet (PG:57)

Chaos Star Effect
1. Fall prone or drop an important item or weapon
2. Suffer severe penalties (one purple or more) to figure related tasks or render them impossible (i.e. break a lock you were attempting to pick, if you also failed the check; get ejected from court for offending a powerful noble, etc.)
3. Suffer an environmental mishap, such as falling from a high place, breaking through ice, or spraining an ankle on debris (fall prone)
4. Discover a new or unexpected hazard or enemy, suffer he effects of worsening conditions (weather, mud, etc.) or otherwise advance the story to the detriment of the active player.
5. Suffer a large amount of fatigue or stress (1-3 short of unconsciousness)
6. Suffer a wound or convert a normal wound to a critical
7. Make an enemy or attract the attention of foes
8. Cause two members of your party a misfortune.
9. Weapon or item gains the Damaged condition or lose your free maneuver.
10. Hamper an allies action (grant them a purple) or other ill effect (Players suggest!)

Sigmar’s Comet Effect
1. Cause critical effect or extra progress on a progress tracker
2. Gain yellow or blue to a future related task or confer bonus to ally
3. Receive aid from unexpected source, make new ally
4. Open a new avenue of approach, reveal an unsuspected information source, or otherwise advance the story for the benefit of the player
5. Recover 2 fatigue and 2 stress.
6. Cause a foe to suffer an environmental mishap, such as knocking him off a bridge or dropping a chandelier on him.
7. Reveal an OMEN, lose a corruption point, or other similar.
8. Opponent drops a weapon or shield (maneuver to recover); or
9. Free extra maneuver
10. Regain a fortune point or Other positive effect (Players Suggest!)