Your Win Condition
Get the extended trade every single time he walks up. Kill him at the level six timer. Alternatively, bleed him out for a 10 to 20 CS gap if he refuses to fight.
General Strategy
D-Blade, Ghost, and Flash. You must get priority no matter what. You need to stay in the lane for a long time.
Trading Patterns
Avoid 'baby trades'—only take the all-in. If he sits far away farming with E, you need to play for a three-wave crash, allowing the wave to bounce back to the center where you can zone him from XP and farm. If he walks up, punish him instantly. You should rush Tier 2 boots for the level six all-in.
Wave Management
Get priority. Slowly push waves one, two, and three for a three-wave crash. Crash the wave around level five or five and a half for a base.
Their Win Condition
Nasus wins by preventing the extended trade and sitting two screens away farming safely with E.
