Wizkids Rules!

While Mary Shazam is active, when you spend an energy she gets +1A.
While Mary Shazam's A is 10 or greater she gains Overcrush.
While her A is 12 or greater she can't be rerolled or spun to another face by opposing effects.

First, when you field Mary Shazam does the energy you spent to field her increase her attack? Presumably this shouldn't count since he was not active when the energy was spent.

Second, does it change if Mary Shazam is already active and you then field a second copy? Would the first die being active then buff the second die's A as it was active when the energy was spent to field that second die?

When you field Mary Shazam does the energy you spent to field her increase her attack? Presumably this shouldn't count since he was not active when the energy was spent.

Correct. The energy to field your first Mary Shazam die will not grant a modifier to that die.

Does it change if Mary Shazam is already active and you then field a second copy? Would the first die being active then buff the second die's A as it was active when the energy was spent to field that second die?

Refer to the following ruling:

https://win.wizkids.com/bb/viewtopic.ph ... 82b3b24be2