Nasus could stand to be more target-agnostic.
Nasus is a Juggernaut. Ideally, this means that he should be effective against anybody who comes and stays within his range, the way literally every other juggernaut is allowed to be.
Of course, every other juggernaut at least has the option to build Black Cleaver. Which means that they can be and often are incredibly effective against attempts to stack armor and shut down their damage. Not so with Nasus. Sheen and thus Triforce or IBG is incredibly core on him, and he has no means to stack BC in a realistic manner. And this wouldn't be a source of complaint, except for the fact that it means instead of being able to whack frontlines in teamfights, Triforce simply adds some of his (frankly, unimpressive) base AD to his Q damage. It doesn't give him any way to get past armor.
Aggravating this is his E. Which is, quite frankly, rather shit. Oh blah blah 'but it does damage and it reduces armor!'.Fun fact, did you know that it only reduces armor while you stand in it? No seriously, that one little tidbit dramatically changes his ability to be effective against anybody who doesn't just blindly stand in his E and try to fight him and/or his turret. Not to mention the damn thing costs ass-tons of mana for basically no reason.
So here's what I was thinking. Instead of just flat out buffing it and having everybody complain about omg ap nasus waveclear wat do, change its effectiveness profile so that it isn't just waveclear from afar.
E: Spirit Fire. Cost: 70/75/80/85/90 mana Cooldown: 15
Magic Damage: 30 / 60 / 90 / 120 / 150 (+ 90% AP) Magic Damage per Second: 10/ 21 / 32 / 43 / 54 (+ 12% AP) Armor Reduction (initial hit): 0/5/10/15/20% for 5 seconds Armor Reduction (per tick): 1/2/3/4/5 for 3 seconds, refreshing with new ticks.
Not anything that I'd expect to go live, but it's more to show the idea I'm working with here. Longer cooldown, much less upfront burst damage, but the damage profile is instead shifted into the dot. It also has stronger scaling, so as to avoid depriving Nasus of waveclear entirely. Most of what it does, though, is give Nasus the ability to fight tanky opponents who aren't going to stick around in his E while giving opponents who might every reason not to.
(I was also going to mutter about my pet peeves regarding base attack speed per attack speed per level for a champion who is perhaps one of the least aspd reliant jugs in the lategame, but I'm sure you've already got the gist of it)
