silly questions but how effective is casting focus with a cap of only 12% (without inscription) IF you use or used to use protection would/did you drop it for casting focus?
Those are really 2 different things. Protection decreases magic resist and slows your casting (separate article somewhere that says you cannot overcap FC to make up for it). Casting focus doesn't do either but gives you a small chance to keep casting through a hit.
If hit procs at the right time it can be a game changer in battle because someone might think they are on offense when you really just got off your combo and only need a spell or 2 to finish them; if they don't react very quickly they die.
Protection protects you from getting your casting interrupted. Isn’t that also what casting focus does? I think that’s what the original poster was referring to.