I'm thinking it's a "Rules Conflict": Perfect Warlord versus Fate.
"Perfect Warlord" ruleset: This character could find holes in the rules that will allow it.
Fate ruleset: Not if it makes a required Prediction impossible, it won't. Ah, just found something I can do within the rules that will stop this tomfoolery.
Also, if this is a "Real-Time" calculator, it may be that Fate has to "find" a workaround and it takes a fraction of a second to "recalculate" with Fate Magic being the last calculation.
I could see if Parson was walking around during his calculations, it would be, "floor's weak here, he'll fall through before casting the spell", then "embers can drop on the scroll here, ruining it", then "ah crap, just drop a beamon his head".
Which could lead to some funny ... well, just imagine this was Parson and instead of a whistle, he was trying to cast this scroll:http://www.youtube.com/watch?feature=pl ... JDo#t=387s