Nasus' Skill Max Order: E → Q → W
Matchup Tip 1: When Nasus whithers you, proc phase rush instantly. This will grant you 75% slow resistance, which essentially renders his whither useless.
Matchup Tip 2: The other tip is that your E cancels his Q auto, so if he Qs you, E him during his Q and his Q animation will go off, but it wont hit you or do damage. His next auto is his Q still, but vaulting his Q to cancel it will buy you time to cancel it from hitting you before you try to escape.
Level 1: Conduct the Quinn Cheese level 1 and then run him down. He will use his E, but you win the trade. Just run out of his E circle and keep hitting him until he is under his tower.
Level 2: Play the slow push game early so Nasus can't lifesteal or get his stacks. His E CD is the same as your E, so keep that in mind because his E will hurt in lane.
Level 3-5: Crash the wave and ping for a dive, dive yourself, poke him under tower for every CS he goes for, or cheater recall. You want to bully Nasus as hard as you can early game, and doing one of these options will grant you the early game lead that you need.
Level 6+: If you are trying to all-in him, ignite him early so his R doesn't heal him as much. Phase Rush is good for this matchup because if Nasus ever wants to be aggressive, you can proc phase rush to out run his whither and escape him when he ults trying to kill you.
Run MR runes because nasus will go E max and his only damage early is his E.
Why Phase Rush? Well, think about how Nasus ever wins against Quinn. Nasus only wins with his W wither ability, where he slows you with wither, which also slows your Attack speed, and then walking up to you to cane you to death.
Now, I go 5head mode on Nasus and counter his legit only way to win lol. If nasus EVER withers me, I then instantly proc phase rush.
The Move speed from phase rush is nice, but I run it because it also applies 75% slow resistance, which actually renders Nasus Wither USELESS!!!! If he withers, you proc phase rush and now you're able to run away to safety until it wears off.
Play the lane very aggressively early, deny stacks, and the most important thing is to try to weave autos level 6 onwards because we don't want to waste procing phase rush in later levels.
If we accidently proc phase rush post 6, a good nasus will immediately wither after your PR is down and cane you to death. If you save it up, then he has no way to ever beat you in lane.
Nasus has incredible lane sustain early, but extremely weak, so make sure to play bully mode because he can't do much if your PR is up.
How to win early if nasus plays passive is to slow push the waves, then when it crashes, the wave will slow push back towards you, and when it does, you will FREEZE AND ZONE TO DENY NASUS FROM FARMING!
Fun Fact: If you blind nasus right when he presses W, you will actually cancel his wither lmfao. This requires perfect timing of course, but very cool if you succeed with it. :)
Also, your Vault can cancel Nasus's Q if you time it correctly since it is programmed as an auto attack, so keep that in mind!