Pattern that pushes the amount of media available to the current cast

[Robotgiggle]

Describe the feature

There's currently no (automatable) way to detect how much media is stored in an impetus. Adding comparator functionality wouldn't really help, since 99% of the time an impetus is nowhere even close to full. Instead, since there's already the precedent of circle-only spells like Waystone Reflection to get details about the current circle, why not add a new one that just pushes the amount of stored media to the stack as a number?

[IridescentVoid]

After this issue was brought up in discussion, it was decided that being able to check in all environments makes more sense, since it is already possible to do similar checking indirectly, using Simulate.