If I have a Jace's Erasure (Whenever you draw a card, you may have target player mill 1) out and cast Prosperity (Each player draws X cards), since we both draw at the same time, for each card drawn would it be
I draw, I can make opponent mill, opponent draws
or
Opponent draws, I draw, I can make opponent mill
Also, if I have Jace's Erasure and instead my opponent casts Prosperity, does the outcome change?