Do stacked foci count as a single focus for the purpose or determining how many foci are used with a roll? The description in Street Magic doesn't mention it save the line that 'It is possible to combine two or more types of foci into a “stacked” focus'. So, are they one focus or several?
And what are the benefits of Spellcastin Focus compared to Power Focus in Anniversary edition save the lower cost? As i understand, you can't use Spellcasting focus to resist Drain anymore.