A good build. Tried out Nasus and it works. Very text heavy though. I would suggest building a section that would feature possible opponents on top lane, along with what YOU think is the difficulty against them, possibly out of 10 (10 being hardest). Adding to that, some advice/tips or any counters against them would help. Some possible top lane opponents could be Nasus vs Tryndamere, or anything like that. Of course, it's ALL up to you.

What you also can do is add a Summoner's Skill section. Both Teleport and Ghost works well on Nasus, but perhaps there are other viable options for Nasus in the case they don't prefer those 2 spells. It should work well together obviously. For example, Exhaust could work on Nasus. An Exhaust following the end of Wither basically shuts down any AD carry. Revive.... just doesn't work for reasons. Something like this might help extend this guide and improve it. Again, up to you.

Generally yes, but this build focuses more on his DPS potential as opposed to his on-hit capabilities.

What chavali said, and isn't getting early Sheen and Phage good for nasus?

Colour is good! ALL OF THE COLOURS! More to come later, yes? Yes. Now go eat something. It's good for you.

Great guide but dont forget to include some color and include some coding like