Here's where the debate is:
If you are using evocation's speed AND METHODS, then shouldn't you use evocation foci/specializations?
If you are using Thaum specializations and foci, then shouldn't your attack spell be strictly like Thaumaturgy IE: a thaum attack spell only has accuracy. It has no weapon rating. Each shift put into a curse adds to the accuracy to resist - it does not add a weapon rating.
I wouldn't allow both.
This is how I do it and I know this is different than how some other people do it:
Your sponsored magic becomes a new element in evocation. So, if you can do biomancy(like summer magic) at the speed and methods of evocation, you can take evocation foci: defensive Summer control/power; offensive Summer defense/control.
From that point it works exactly like evocation: weapon ratings, block, attack - exactly like evocation. With the exception, that you could justify skill replacement spells with evothaum and, maybe, wards.
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If you are going to allow Thaumaturgy foci for you evothaum, then it gets weird. Control stays control, but what about complexity foci? do they become a stand-in for Power foci?
If you are going to allow Thaumaturgy foci for evothaum, I would have spells work exactly like thaumaturgy: no weapon ratings; Block are done as wards and can only be set up on thresholds or doorways/intersections; veils are immobile.
Otherwise, anyone with sponsored magic will throw all their foci into thaumaturgy and will be able to get twice the mileage out of those foci because they'll double as evocation foci. Once you start piling on refinements, things will break down quickly.