Nasus is useless if your team isn't ahead.
Just spent half of last game farming top lane with a Nasus, while I couldn't stop him from getting stacks, he wasn't even a threat, even with 214 CS or 642 stacks. This was partly because our team was ahead in kills, so all we had to do with kill everyone else and focus him once it was done. I'm starting to regret the 1350 IP I spent on his purchase, 5 months ago.
"My 500 stacks were for nothing."
- Nasus commenting before his team defeat