Mana Mastery

Mana Mastery 
This ability allows the character to activate
up to four spell slots simultaneously, adding
their ranks together to cast a spell of equal
rank to the sum.

If we utilize Mana Mastery in casting a spell, should we be calling our attack at all differently than if we had used a single spell slot?

You should call it normally, but be prepared to explain what combination you used in case you are card checked.