It's possible we're talking at cross-purposes here... I don't mean to be using a "hero" character as game-world normative. There are hundreds (maybe thousands?) of "normal" folk for every hero/villain bad-ass character.
I'm not trying to find a way to create the "one-shot take-out." I'm trying to AVOID it... while keeping the narrative intact, the sense of the universe being cohesive and internally-consistent.
Most mortals are fragile, and squishy.
(Edit: I see that blackstaff67 has highlighted just this point)
No. That would suck.
It would be completely unfun if everyone who failed to buy a Toughness Power was always one turn away from a completely arbitrary death.
I DO agree that "one-round win" is a pretty sucky thing, RPG-wise. That is "mook" turf, and the players don't really want all-mook opposition, and CERTAINLY don't want to BE mooks! But I would suggest that -- if you are up against an allied pair of vampire+wizard -- you are NOT in a "completely arbitrary" situation!
One element of not needing "everyone buys a Toughness Power" would be relying on the GM not to send overpower'ed opposition at the players. Another is for the PC's to be smart (researching ahead of time) & tricky, and all the rest; and be ready and able to defeat the wiz/vamp pair when they face them!
If you read the novels, you'll note that Harry's not dead. Despite being a squishy human, who's been up against much worse than one spellcaster and one vampire working together.
Murphy's not dead either. Nor's Michael. In fact, the novels make clear that killing a human hero is really damn hard. Even with various magical powers. Which is good, because otherwise the supernatural action that this game is supposed to be about would kill most PCs within two sessions.
But for "ordinary people," a lone wizard or vamp (let alone the pair!) should suffice for a 1-round take-out. It may not happen to Harry, or Michael, or Murphy... but it happens repeatedly in the stories to minor characters. The supernaturals are DANGEROUS, and most people are essentially defenseless against them.
The wizard can maneuver and pass a tag to the vampire. The vampire can invoke it for +2. They can't arrange some kind of instant-victory combo. And they certainly can't bypass the consequence slots that are supposed to let important characters fight on.
I'm good with that; in fact, that's exactly what I want, too.
But how do we rule on a "Sleep Spell" which causes sleep -- no more, nor less, than "Asleep" -- as a result of the spell?