I've found, when running the game, that in a big confrontation with the Shadow it's a really good idea to tease out the stage of Reality Changes where both the Shadow and the Solipsists get to spend tokens (Shadow tokens and Infestation) to alter the result.
What I mean by this is that you can do a back and forth process, spending a few tokens at a time and narrating the struggle for control within the change. First work out the difficulty without Shadow tokens, then spend 1 or 2 Shadow tokens, and have the GM narrate how the Shadow is warping things to make the change harder. Then if the Solipsists spend some Infestation have them narrate what extra things they are throwing into the change to counter that. Then spend some more Shadow Tokens, and so on.
The effect of this is to create a tussle for control much like a fight scene in a movie, concentrating on the details of how the Solipsists and the Shadow are wrestling for control. I did something like this in the final scene of The Circusites at Conpulsion 2008 and it was really satisfying.
Note
The basic difficulty of the change is set in step 2 (set difficulty) to be equal to 5 + the number of general shadow tokens, it doesn't go down because you then spend a token in step 6. So if there are 5 general shadow tokens in play and then you spend one the final difficulty becomes 12 (not 11). Of course a subsequent change will count the shadow strength at 4.
Thanks to Diego from Italy for pointing out the possible confusion in an email.