Yeah, as an end boss, he'd work well. I like the ideas presented. Especially if you start him off with just a single lawbreaker stunt, I could see him slipping through the Warden's cracks. As he gains in temporal power, he gains in magical power and eventually, he'll come to the attention of the PCs.

If one of them is a Warden by that point, drama.

Don't forget, though it has similar issues, you also have the Column system. For a relatively focused character, two or three wide columns will serve quite well.

As Taran said, it's down to your table, but my take is this:

Shapeshift into a mundane animal (even if several pounds heavier than any living mundane animal) and you're in the clear. Damage caused is still mundane, since you had to learn how to do it.

Shapeshift using some variation on the Hexenwulf, and you're in a gray area, but zealous Wardens will likely see Black. Damage caused is mundane, but backed and supported by magic.

Shapeshift using some willing variation on the Loup Garou and you're solidly in the black. You've got a demonic co-pilot whom you've willing invited in, and you've surrendered control to it willingly. Damage is caused by magic, and is in no wise 'mundane'.

Stars and stones, some of that is utterly incredible.

I agree, it can be difficult to deal with the kind of power a Wizard can throw. In an online game on a different forum, a brand spanking new Wizard, through use of Foci and such, tossed a 7 Shift Evocation and came close to one-shotting a bad guy.

I don't expect that the GM was thinking this guy was going to be an epic fight or anything, but I'm sure that it wasn't expected to be that quick, either.

Now, part of that was also the randomness of the dice. On top of the 7 shift attack, I also got a really good roll against the antagonist's bad roll.

Personally, I think I'd run it more or less like this:

A Wizard's base Evocation is just like any Fate attack. In this case, you roll Discipline just like anyone else would roll Fists or Weapons. And the effect is the same. Shifts become Stress. And this doesn't cost the Wizard anything at all.

A focus with a Control boost helps you do more damage because it helps you control more power in the spell, but there's no Weapon Rating at all. (This also helps to show how someone like, say Luccio, can toss around pretty seriously damaging spells near constantly without dropping).

If you want to pull out a big Evocation, then you're working with Stress / Consequences, and I'd say go with something like the following:

Conviction = Power still. Foci Power bonuses apply. But for every 2 Wpn rating you send (Round down), you pay 1 Mental Stress. So a Wpn 7 Fire Evocation would cost 3 Mental Stress.

Yep, that's a lot. I might allow a player to use taggable Aspects/Maneuvers to reduce that at a cost of 1 Stress per tag, minimum cost of 1.

Maneuvers and normal blocks, I'd do the same. If you're just going for a general 'magical' option, Roll your Discipline and take the result of the roll, just like anyone else with any other skill.

If you're trying to draw heavily on your Power (i.e. get that as a bonus to the effect of a successful roll) then you pay just as with attacks.

On the one hand, this lets Wizards fight a little longer and with more frequent magical oomph, but also allows them to bring out the big guns if they feel they need to.

I'm not sure I'd want to even give this one a try as a GM. Too much chance to overkill the character when you choose to take consequences.

Still, if someone wanted something like that, I'd say 'Define how many Focus slots you're using. Okay, take a Consequence at that level (or 1 higher, if the number is odd). That consequence stays with you as long as you maintain that focus. It's not available for any stress reduction, and you don't get any free tags on it, but you get your focus slots. -6 is the max you can do, though, and I wouldn't let any player have more than 1 'consequence focus' at a time.

Were-Unicorn?

Physical Immunity to magic, define it as working against Mental and Social stress and Consequences, but only if such are direct results of magic.  So if a wizard causes a gas main to explode, he takes damage, but not to directly evoked fire.

It's expensive, but immunity to magic would be.  Though I might grant a minor reprieve to the cost for being immune to beneficial magic as well - maybe.