Our grey wizard completed his career and switched to charlatan. How much does it cost him in advances to buy a spell from his old order?

jh

In theory (and IMHO) once the character has the specific school of magic talent card ("Grey Order" in your example) they can buy spells just like any other action card.

"A Wizard may only ordinarily learn and cast spells with either the Basic trait or with the trait of the order matching his order talent card" Learning Spells - Player's guide P116.

"Action card: taking this advance allows a player to select a new action card to add to his options. Some action cards may have special requirements - for example, only wizards can aquire new spells, and even then, the wizard can only aquire spells from his paritcular college of magic." General Career Advances - Player's Guide P43.

Once a wizard, always a wizard!

Yup, I go with you must be in a "wizard" career to learn spells.

I require narrative background for all talents, actions etc. This can be as simple as "I was roleplaying bossy last session, so this Air of Authority makes sense" yup, or an Interlude action palling around with a source of some talent etc.

Since he's swapped careers I'm:

a) Not allowing him to use his order card until he 'rejoins' the wizard career tree

b) Spells cost double until he rejoins the career tree

The same thing happened to my Initiate of Ranald. He switched to Assassin.

jh

I'd agree with Emirikol somewhat in handling this, although I am a bit more restrictive.

The PC is no longer focusing on magic because they aren't currently in the wizard (or priest) career. Thus, they will not be able to learn *any* new spells until they return to a spellcasting career and make spellcasting their primary focus. I won't deny them the Order card, though.

After all, if you switch careers from wizard to assassin, for example, you can't train Int like you were in the wizard career, and you can't buy the skills on the wizard career sheet. Since spells (and blessings) are tied to the career as well, IMO you would need to currently be in one of those careers in order to purchase spells/blessings too.

Of course, I also take the career lines for wizard and priest very seriously, like Trollslayers. It is tough and a big story-event to leave the career path ... and nearly impossible to get back into it. In my mind, you essentially had a change in character personality/goals and have forsaken the organized church/college to pursue your own goals. The church/college aren't really all that forgiving in my Warhammer world. While they might not send witchhunters/bounty hunters after you (depending ... because they actually might), chances are pretty slim (to none) that they'll let you back in. If my PC wants to diversify their skills, they can purchase non-career skills.

I once asked FFG how to handle priests who left their career. The answer was something like: "It's up to the GM, but context matters in this case. Did the character lost his faith, or did he choose to pursue his calling on the other path. Mechanically, characters who purchased their dedication bonus, and keep their Priest career ability card, retain the ability to both invoke and learn new blessings."