I was assuming you wanted stun to mean they can't do anything, but simply tagging for a +2 is totally appropriate.

Yeah.  You answered my question, but I was just clarifying the meaning of that sentence.  If I do a maneuver, anyone can tag the aspect for free once or with a fate point thereafter, but if I want the PC to "Do nothing for one round" because he's stunned, I have to offer him a compel and pay him a fate point if (s)he agrees.  I think that's what you were telling me.

Wow.  8 shifts of power.

It's powerful, but I'm playing in a game where the wizard has power 7 rotes.  I'll be taking over the dming soon, so I want good opposition.  We're a 10 refresh group and he has +5 conviction along with foci.
That's why I used power 8, but the number was intented to be a bit arbitrary.

You could do a maneuver and then tag for effect too.

Like, if you are using air, you could do a maneuver for the aspect, "Blown away".  Then you could tag that aspect for effect.

As GM, I would rule that the enemy flies back at least 5 zones, taking damage from anything behind it in it's way (whatever is thematically appropriate.  Drywall won't do much to a character with supernatural toughness).

Anyway, depending on how that plays out (like if you were smart and maneuvered yourself to made the badguy slam into a brick wall) I would give the enemy various consequences as well.

8 shifts is pretty hefty.  An intelligent 8 shift maneuver would probably kill a ghoul.

Sort of like just hacking at a critter with a sword is not always the way to go.  It it usually better to stack up aspects and then do a maneuver like, "slicing the neck", with an impressive roll.

If a player invoked that for effect, I would rule the monster d-e-d dead, unless it is not thematically appropriate.

-IF YOU JUST WANT TO STUN THEM-

You can use spirit to take someone out in their stress track, or more easily (and not skirting the laws of magic), apply a maneuver with spirit, "knocked out".

In my game, as long as you win by 2+ shifts, I'd let you invoke that maneuver to effect and the perp would be knocked out.

If appropriate, I'd let the perp start rolling endurance to try "coming to" after about 2 rounds.

However, if your attack was 8 shifts, I doubt they will be able to make an endurance roll for that anytime soon.

Tag to effect...I've seen it in one of the example spells...the "grasping branches" spell YS,pg294.  

To get this straight, your guidlines are that if you succeed by 2 shifts you can tag to effect?  Officially, are there any guidlines for this?  When you say "invoke for effect", are you giving the perp a fate point?

Also, how can you kill something with a maneuver?  I thought the purpose of a maneuver was to set-up killing blows and fancy moves.

If I did a maneuver to knock someone out, what's the difference if it's 8 shifts of power vs 4?  If the the perp fails, he faces the concequenses.
It also seems a bit powerful to be a maneuver.  Wouldn't you have to just do piles of damage until they conceeded and said "they're knocked out"?

Yeah, that's the idea.  It might be easy to resist at first, but then get harder each time it happens.  My idea was to have separate mini-events described to each character prior to the start of the campaign, just to get things rolling and give them each a goal or interesting tidbit to look into.

The shapeshifter mini scene was to wake up naked in the woods with a half eaten deer beside him.  Something to say, "oh, that's not normal!"

When he first gets hit by the "attack" in-game, he'll have an idea of what might be happening, even if he resists.

There are two things to consider:
1) Is this just a plot hook to get the players investigating?
2) Once the PCs are investigating and aware of the problem, can this attack actually be used against their shapeshifter?

If 1, but not 2, then keep doing it the way you are doing it.
If 1 and 2, then you will want to find a fair way to stat out the Transformation attack so it is a challenge to be resisted, an actual struggle, rather than simply a cheap way to incapacitate the shapeshifter. The shapeshifter may end up opting to stay in another city while this is going on, so as to protect his or her friends from the risk of an uncontrolled transformation.

I was thinking both 1 and 2, although he wouldn't have to leave the city because the radius isn't going to be city-wide.  I figured he'd experience one or two strange events, maybe be carrying around a moderate mental consequence.  There will be an NPC experiencing the same things, but will  be worse off and  that will give them additional clues as to the when and where things are going on.  But I figure, in a full-out fight, this power could be used against him.  This is why I want to figure out the power/attack.  It sounds like a power that might be better done as a spell resisted by discipline.  Some kind of mental attack from afar.  I'd only do the "you wolf-out and don't remember what happened" as a compel, but not in an actual fight.  But you're right, it'd suck if he chose to sit out and not risk his allies.  While I don't forsee that, Players always do what you don't expect.   Fortunately he has the aspect, "never back down" 

If you're Playing Dresden in North Bay, ON, READ NO FURTHER.

o.k, so I have an adventure idea that revolves around a shapeshifting party member.

A bad guy summons a demon to get it to do nasty things.  In return the demon wants the freedom to do as it pleases (this is a very, very rough explanation of the pact)

My idea was to have an entity who attracts  shapeshifters in a large area to him(several kilometers radius)and "forces" them to want to shift into their particular forms.

The reason the entity does this is because he's stealing their "human form" so that it can eventually walk among the mortals without having to use his energy creating a physical form for itself and no longer needs to rely on its summoner to stay in the mortal realm.

Everytime the demon forces shifters to change form, it steals their human side, eventually leaving their animalistic sides behind.

So a shapeshifting wolf, would become a wolf always.  Or, for instance, a human who gets an aspect of the wolf during the full moon would run around thinking he's a wolf during the full moon, but any other time of the month he'd be catatonic because there would be nothing human left.

So how do I do this?
One way I was thinking of giving the PC Plot driven "involuntary Change" and tying it to an aspect. (he'd get an extra refresh until they solve the mystery or until he's driven mad)
I was also thinking of giving the demon a form of "incite emotion" (to get them to want to shift) and " eat power" to steal abilities...but you can't really steal non-abilities, ie: humaness

I want to give the PC (and the other shifters) a discipline check to resist the compusion which gets harder everytime they are affected.  So another way, maybe, is a spell that causes mental damage, with consequences that I can compel like, "must go hunting" or "wants to be a dog" etc..that way they can slowly insane and when they get taken out it means they've been fully transformed.  But what kind of spell would that be and what would the mechanics of it be?  It would be cast from a Place of Power at the very least.

One thought might be that your aspects might be compel-able, but are they compel-able for the campaign? The party's aspects just might  not fit for the adventures. Either that or try to self compel more. IMO it should not fall entirely on the gm to give you fate points. there is a lot of this game that says that narration and the story falls on both sides of the GM screen. So if you're aspects fit the campaign and you want more fate points, you might have to work on getting them yourself if the GM is unwilling to give them to you. And if the entire party is having the same problem then maybe if they see you do it they will hopefully follow suit. I know this is always the easiest thing to do but will hopefully get better with time.

I wonder if this might be the case.  I do self-compel more than most players and it's a bit of a general agreement in our group that we should just self-compel instead of the DM doing it.  It sometimes feels a bit forced, though, so maybe my aspects don't fit with the current story line.

That said, I seem to be getting the sense from the comments that more compels/fate points, in our game at least, would be better.  I'll keep a tally in our the next session to get a better idea of how many points are being thrown around...maybe pipe in again earlier in the week after the game.

Mostly, I just want to get a handle on things for when I run a game, and if I can find ways to make a good game even better, that's a bonus - we're all newbies to FATE.

Thanks to all for the input.  I think my question has been answered, but feel free to add anything more if you think it'll help!

You can always compel yourself. It's right there in the rules, even.

Gah, "Compel yourself," kicked off a Madonna song in my head, because the cadence is so similar to "Express Yourself."

That's how it works usually.  I'm partyly asking the question so that when I GM, I have an idea of how much to give out.

I also believe that my aspects are sufficiently compellable...and some of them can be compelled more than I can use for a bonus.