Has anyone experimented with revoking spells?
I imagine the default option would be to revoke each spell after it's been cast once, to remain in "balance" with the wizard, but since it's such a subjective call for the DM to make, it seems ripe for interpretation.
In particular, I was thinking about using it to "signal" the cleric player about their god's desires or intentions, but you could instead interpret the "boons" granted by the cleric's deity for abiding by the Precepts of your Religion as the signal to give the player back a spell of some level.
Whoa, actually, you could have a pretty heavy-handed god acting kind of like a Shadow from Wraith, putting weapons in the character's hands when she needs healing spells, for instance.
You could dial in very close to the cleric's "arc" for a bit by carefully interpreting boons and revocation, just like the wizard-class can be put in the spotlight with use of the move Ritual. Their magic is what makes them special, so the game puts in these "interpretive" little tidbits to liven things up when the mood strikes.