Southperry's damage calculator - Magic damage.

In the example below, I'm using arbitrary numbers for Int and Magic Attack values, as I am under the impression that they contribute equally to the damage output (verify please.)


Inputs:

• Total Magic: 1150
  
• Spell basic attack: Maxed Blizzard, so 570.
  
• Mastery: 60%
  
• Magic Amplification: Maxed, so 135% (?)

What am I doing wrong? Or am I understanding something wrong here?

EDIT: Checked and maxed Amp is 140%, still doesn't cut it.