Guillotine Cross: How EDP works with Cross Impact?

If my ATK 200 + 300 on status screen, when EDP activated it should be let's say 200 + 1500 (multiple by 5), so my total ATK is 1700, now let's see about Cross Impact lvl 5 when EDP activated (half dmg multiplier), the formula should be :

{(1400 * 0,5) + 400}% * 1700 = damage

or

(1400 * 0,5%) * 1700 = damage ?

+400% because I heard EDP give +400% at the end of damage multiplier or am I outdated? =.=

Thank You