If we have a plain set of rules, peppered with traits that provide light exceptions to the rules, where does magic go?
Yes, this post's content has probably already been formulated somewhere, somehow, as Grumpy Wizard stated in his review of the Elusive Shift.
In some games, players acquire special tokens, that, once expanded, allow them to re-roll some attack or check. At this point, the imaginary web of the story gets stitched up.
What if such stitching became the exclusive domain of the magic and the spellcasters?
Casters would have a say in the shared maelstrom of imagination, paying a certain price, they could rollback and alter the story sewn up until here by referee and players.
(forking idea now, casters pay in years of life, the referee knows how many years the caster has been granted, he negotiates with the caster player what each alteration costs, in months or years of life, at some point the character will be exhausted)
Mana points could be used, instead or along months or years of life. The caster would seek to alter the maelstrom, the collective dream, and the referee would state the cost, or simply say, "you can afford it", letting the range of the depletion be revealed after the spell has successfully done its stitchup.
In an ambush, the caster doesn't fire magic missiles, they tear the thread of the story and restart it so that the party was not surprised.
The other players should be prevented from intervening in the caster's labour, they should play along the change. Should a player explicitely request the caster's intervention, they too should pay a cost. There would be no commandeering the caster around, "hey, cast a fireball". The old man is around, a lucky-charm for the party.
(the other characters fail to understand what the caster does. What if the caster fails to grasp it themself and the cost is exacted against their sanity?)
Time to roll this idea back.