Okay well all you need to do is play malzahar well. also the order between archangels and cap is completely up to you the main point is to get them all. The hextech revolver is for early spell vamp and you can sell it to buy your last archangels and sell the dorans to buy cap also try to drop your malefic visions on him then ulti and if possible a nullvoid under all of that would be good. At end game your main damage dealer will be null zone because depending on amount of stacks you will have for about 15% to 20% of hp a second that will kill almost anyone with your ultimate and malefic visions.
this is my first build i hope you find it useful.
PS the zhonyas is supposed to be cap and make the boots into ionia

updated with cap patch