How much Dmg am I actually doing?

So I am trying to figure out how much +Ability Power I am getting when using certain abilities. Here for example ------ Passive: Fizz's attacks rend his enemies, dealing 30/40/50/60/70 (+35% Ability Power) plus 4/5/6/7/8% of the target's missing Health as Magic Damage over 3 seconds. (Max 300 vs. minions)Active: For 5 seconds, Fizz's attacks deal an additional 10/15/20/25/30 (+25% Ability Power) magic damage on hit and apply Grievous Wounds to his target, reducing incoming healing by 50%. ---- Lets say i'm just a standard level 18 starting and my runes I have give me +18 Ability power and for giggles lets say i'm maxed out on items giving +120 Ability power for each so a total of +720 ability power. Once I use the attack how much damage in magic would I be using? (for fun lets say the enemy has no magic resist just plain Jane that would make it true damage.)