Generally, you just have to adapt it. That's what I do. I take the basics and apply them. Which is why, I suppose, T1 is easier for me to get.
Losing preps is fine, I have no issue with losing them if you catch me prepping with an attack, but if I successfully make it, oh well. But that's just something people have to agree on. Do you lose a prep per hit, no matter how far back, or just whatever one you were working on in the post prior.
Hypothetically then, deactivation wouldn't work. To me, he doesn't have to specifically mention the sword's target being the magic circle, but it would make better sense too - unless in his universe all magic pulls from the same thing, so fire magic and water magic(as an example), are really just the same force being manipulated differently and his sword cuts literally at the base compounds of it.