You can start tear against nonpokers to save 300 gold, but take corrupting start against pokers. Seraph's, right now, gives 100+AP, 10AH , 250HP and a VERY BIG SHIELD(500+), making it the most gold efficient 2nd item for Fizz. Gives more DAMAGE and enough survivability to compensate for delaying Zhonya's till 4th item.
192+ AP spike on 2nd item makes Rabadons the best 3rd item. Also Fizz likes raw AP very much because he has low base damage but high AP ratios.
Transendence and adaptable haste are making it possible to go Sorcerer's instead of Ionian Boots.
Quick Fizz AP Mid Build
Best Overall Build