The best way, I think, is to use enchanted items for this. An enchanted item with a block on it can be used reflexively pretty good, since you can just argue, that it is always there, it just only gets a use at this very moment. Rotes are probably a good way to go, too, since they are basically the same thing, only they cost mental stress. Narratively, I see a slight difference. Since you sometimes only have a split second to react, it seems implausible to use a rote spell, but for example an enchanted coat will always have been enchanted. It kind of brings back the "always on" enchantment from the beta version of the rules.