Modal spells are always great fun; they let you pick between multiple options when you cast them, making them very versatile and able to deal with lots of situations with fewer cards. But how do modal spells work when you copy them? Normally if you copy something like Boros Charm with, say, Reverberate, you don’t get to pick a new mode. Your copy has the same mode as the original; you don’t get to pick a new mode the way you get to pick new targets, because nothing says you’re allowed.
That’s not true of a few off-the-wall copycats like Chandra, Pyromaster though. Chandra, like her friend Isochron Scepter, creates a copy of a card you put into exile, and lets you cast the copy (or copies, in this case!). Since you’re casting the three copies separate from each other, they can have different modes. So, if Chandra found you a Boros Charm, you could make everything you control gain Indestructible for the turn, blast your opponent for 4, AND give a creature double strike for the turn. Or you could blast for 12, or give three things double strike, or whatever combination of those modes you prefer.