Old-timers will remember the glory of Whimsy Cards. For those who don't, I just wrote a detailed article about them at Project: Redcap. Give them a try; they're a blast!
They look pretty cool. I especially love the rule you have for how many each player gets per story.
Thanks reminding me. If you have other ideas, please, write them. Any new card which was very handy for the GM?
I was fond of one we invented, "Goodwill from an adversary." It really made Hermetic rivals more three-dimensional.
Nice. I like that.
It sounds promising. However it is a bit hard to imagine how a player find out what goodwill the enemy can provide.
Adversary isn't the exact same as enemy.
It could be a contestant/competitor situation. I wouldn't expect goodwill from a mortal enemy. I might get goodwill from a political enemy, but because he wants something later. 
If the mortal enemy sees you down, he's likely to kill you, or the whimsy card might signify the transformation of the relationship into something other than being a mortal enemy... For example, two mortal enemies coming together because of an even worse enemy shows up. Yeah, I like that.
The player doesn't need to find out. The player makes it up, and the storyguide either takes the idea, modifies it, or vetoes it.
I can see lots of ways that it could be used:
- an adversary waits for a character to pick up his sword after botching and dropping it in a duel.
- an adversary incapacitates a character, and then provides immediate first aid, and later returns the gravely injured character to his sodales.
- an adversary in combat catches and rescues a character who falls off a city wall.
- an adversary changes his mind and stops summoning a demon to slay the character, allowing the character to flee instead.
- an adversary offers mercy/freedom to a defeated opponent.
- an adversary allows a character to disengage and flee from combat.
Even most "mortal enemies" (especially human ones) are unlikely to actually be genuine psychopaths, and may well have either a conscience or moral ideas (or an honour code) about the "right way" to "win".
Of course, not all adversaries would offer "goodwill" in all circumstances, and an adversary might have an ulterior motive for doing so (even if that motive is merely to preserve their own conscience). However, I think it is quite plausible in lots of circumstances. It's a great story-telling idea.
Thanks, I understand it better this way.
This is the start of a beautiful friendship. 
That would be a reedition I'd LOVE to buy!
They are also very easy to make for yourself.
Oh, someone anonymously updated the Project: Redcap page to point out that Sub Rosa #7 includes a printable PDF of Whimsy Cards. So you can buy them!
Oh, I did, but they're not very pretty.
My copy only points to the website with the cards' text.