Mirror of Evaluation
A Mirror of Evaluation is a tool very similar to the ever-useful Scroll and Quill.The main difference is that it greedily casts any part of the spell it can while it is being written.
Say for example you write a subcircle with two more subcircles, each containing a Foundational Delusion.
When drawn, the glyphs of these subcircles will become literals for the number 2.
Then, you can draw say, an Annexation Stratagem in the parent circle of the two twos.This will immediately consume the two subcircles and evaluate to a literal 4 as a glyph in the parent circle.
The best way to understand these workings is absolutely to try them out for yourself:

It's worth noting that, while it casts any part of the spell it can, the mirror still stores the spell its holdinginside itself as an inscribed spell.
Thus making it accessible to all conventional spell reading and writing methods.