it's a Dresden Files game
if it's not in the wikipedia article, fudge it

Blasting a mortal is a really heavy handed use of evocation. You'd get better results with a "suffocate till unconscious" grapple

'blast' is an incredibly vague term

fire: 'blast' the area with a sudden but diffuse increase in temperature - inducing hyperthermia (ie. heatstroke) - secure the mortals, drag them away from the epicenter, and get them some basic medical attention; slit the throats of the non-mortals at your leisure, or whatever
air: shockwave effecting sudden increase in air pressure accomplishing similar
water: ...we've seen very little of what this is capable of accomplishing, so I'm less sure of how to go about it
earth: dramatic increase in gravity until targets lose consciousness spirit: induce sleep...or just club folks upside the head

If I end up GMing, I know that the easiest way to dial back on that power for magic characters is to have more than 1 big bad, and to include mortal enemies.

Can't blast a mortal, and can't use everything up in one shot if there are 5+ bad guys around.

Challenge accepted.

I think a lot of people discount the mortal, and it's just because they haven't seen a proper one in action. I'm not arguing that one can stand up to Titania, but they should be able to almost hold their own against a supe of relative refresh.

The MERLIN would have trouble trying simply to not be wiped off the face of existence in a full-on confrontation with one of the Queens.

Kind of situational really.  I mean, if it allowed the use of Discipline as a dodge against any attack that would be absurd, but depending on how frequently PCs are the target of Evocation effects it could almost never come into play.  Also, consider that it would be taken en lieu of another Specialization when comparing relative power level.  To take Harrry's life as an example I have trouble thinking of any situation where it would have been useful at least through book 5.

Confrontation with the Shadowman
Confrontation with Mavra
Confrontation outside Bock's (been too long since I read that one, spelling might be off)
Confrontation with whats-her-name the disciple of Kemmler in that alley wherever it was [ (okay, okay, I'm already re-reading the series)
the aquarium incident
...
did the confrontation with Shagnasty on the hilltop include Dresden-bound evocations?  I don't recall

As was also mentioned earlier though, if someone doesn't take consequences then you have missed. Doesn't matter whether you're throwing a punch (weapon:0) or shooting them with an assault rifle (weapon:3) or even hitting them with a mack truck (weapon:5) if they don't take consequences then they are perfectly justified in saying that you missed them entirely.

And even if they DO take consequences from an attack with a mack truck, that consequence could be merely 'abraded hands' from their desperate dive out of the way.  The truck missed, but they still took stress and a minor consequence.
Heck, they could take the severe consequence 'shattered ankle and foot' and say that that's all that was in the truck's path.  They dove out of the way just a fraction of a second too late, or inches too short, and the truck impacted / drove over their foot.  They'll need medical attention to make sure it doesn't get infected, but by no means should they just up and die from that.

If it's just another dark alley with no special significance, then the character has no reason to walk down it.  And that's where the fp come in.  They're an incentive for the player to find whatever thinly veiled excuse might be available to serve the needs of plot.

Except perhaps in obscure plot-assisting scenarios possibly involving a compel, of course.