Hi! I’m thinking if brawn should rather be defined as:
brawn_{i+1} = brawn_{i} − D
with
D = {brawn_{i}}/2 + wd
For clarity.
Otherwise this is rather simple and cool. I really like cast(mt)
A quick hack that I like with all magic casting systems would be defined as
mt = Cunning - M + bleed
where
bleed = brawn_{i} - brawn_{i+1}
just to make cast(mt) more accessible in dire situations