And golem will give more with much mana , i had something like 380 , 400 with tihs build :)

Look very good at m asteries, dont use mana reg 3 , for me its usless , with all those items you have soemthing like + 130 and this 5 + dont give a difference but 5 % more mana does cause it give 50 + ap

gl testers :)

yeah the second build is 5 archangels staff and 1 zhonyas ring witch have much more dmg , and ulti 1500

Core items 4 archangels staff , 1 sorcerers shoes , 1 zhonyas ring , if the game will be really fair and ballanced you can sell shoes and buy 5 archangels staff, depends on what you want, 900 ap and 380 move or 1100 ap and 310 .

Just some thoughts about your last two comments:

1st: Dont use requiem, when they are about to kill you: Taking damage does not interrupt the channeling - dying does. So wait until your dead, and throw your ulti then, as it cant be interrupted anymore.
2nd: No matter what the description reads: after you used your ulti, being dead, you wont be able to cast any other spells, your 8s are over. So activate defile first, but make sure that you'll still have enough mana to cast requiem.

Beside that, you are buying rod of ages too late to benefit from its whole effect (unless youll let the game become an ugly late game, which we intend not to do), and CDR-runes are wasted on Karthus.