the first 5 items is core items in my build.
It gets you good amount of protection, damage, and utility.
You have some good MR, Armor and Health from almost all items, and damage from all but boots.
Here comes the the last item.
Here you just get what u lack. Phantom Dancer is just one answer.
In defense armor, Thornmail can help u more then above item, if lots of ad enemies.
randuin's armor give best of all world, (extra damage from atma]] and synergize well with
Nasus.
Even Guardian' angel can be good, but dont help in damage wise ways, or utility.
If to much Magic damage, Banshee's Veil is really good.
Need More damage instead of what phantom gives, Bloodthirster is the best option.
The last item that is a really good choice, that gives much great things
is Madred's Bloodrazor