I think as long as the player is following the rules, he cast the spell, uses extra shifts for duration, it is fine. If he is using it in a fluid situation, even if it is social "combat", he needs to use Evocation or Evothaum to do it and take stress for it.

Except at that point it's no longer a simple action, its an Attack, Maneuver, etc... which don't have a duration. I can see adding duration to allow you to prepare it in advance and save it for later in the scene/day, but not allow you to use X number of shifts repeatedly until the duration ends. (barring a far more expensive ritual along the lines of what Haru suggested)

Solve Improbable or Impossible problems... first you need to address what the problem is. I don't see this as "I'm socially incapable, so I want to boost my social skills" I see it as "I want to manipulate this guy into agreeing with me." The goal isn't to raise you skill so you can do what you want with it, the goal is to accomplish X by temporarily increasing/replacing your effective skill.

The Duration and Enhanced Evocation section on 265/266 says that thaumaturgic spells that inflict consequences or temporary aspects on living targets don't have a base duration of "until sunrise." They don't have an intrinsic duration, they happen and they are done. The effect they caused might last just like a normal consequence or temporary aspect.

True this power would only shine in certain builds, but the same could be said for just about any power. That alone doesn't mean it's balanced.

I can't think of any off the top of my head, but are there any powers in the YS that manipulate the skill point economy like this? (replacing or moving trappings to another skill?) Or is that limited to stunts? I'm not saying that you CAN'T do it with a power, I'm just curious to see if anybody knows.

Defense trappings are nice, but there are already so many skills with them that for most characters, this power amounts to a ~+2 to two trappings without breaking the skill cap.

That depends on the character really. The OP appears to both be a melee combatant and a caster so his skill pyramid is probably pretty cramped. I'd wager it's probably a fair bit better than +2 to two trappings for his character.

That being said, shouldn't a power be balanced on it's potential for imbalance rather than it's balance in a single instance? A +2 makes a mediocre person halfway decent, and a very superb person freaking awesome. This power could potentially take a mediocre person and make him superb in two different areas, with no limitations.

On a marginally related note, what is your take on a stunt that allows you to move the attack trapping from Fists to Athletics? On the surface it's the reverse of Footwork, but would also completely negate the need for the Fists skill.

It was a pulp WW2 game, but I was rolling in FP's thanks to my aspect of "I Didn't Think That Far Ahead".

Just to clarify, it wasn't consequences, the group's WCV placed two separate "Fear" aspects on him during his previous 2 turns. And I believe it was Inhuman Strength that got you that last +2, not the stunt. (you weren't using your sap gloves)

But yes, I was a little shocked when my supposedly bad-ass Gang Lieutenant flew across the room, smashed into the far wall and was knocked unconscious before he could do anything cool.

The Jacks are still going down though. 

Helping take down the bad guys is not the same thing as being redeemed. I'm assuming he's not a full on Wizard level talent otherwise he'd be in the White Council already. The Wardens keep an eye on Sorcerers in general to make sure they don't turn Warlock... those that have already had a taste of the dark side are watched even more.

You may want to decide why he wasn't executed right off the bat. Anybody with Morgan's school of thought would have probably done it.

Have the laws been explained to the aeromancer, btw? In Character I mean?

The way I see it you can have the White Council get involved with him as mentioned above. (I'd also have the Warden call him 'Pup' or some other mildy derogatory nickname until he supplies a real name for his character)

You could also have his dark past return as well.  Minor practioners hear rumors that he was in a cult and put the leader down... now all these magical n00bs think he's the best thing since sliced bread and want to be in his cult.

Even if he says no they can form a cult anyway and do things in his name. If they catch a rumor that he thinks somebody should ward the library, they go and do it for him. If they think this aeromancer would take out badguy X, they try and go do it for him. Then other badguys can get pissed at him because 'his' cult tried to rough them up.