I agree and disagree on alot of your points.
Also, you bring a lot of interesting discussion. I feel like this thread is old now, but I'd really like to continue this somewhere else.
Things I agree on:
inability to splitpush, as most of your opponents will be able to deal with you under turret in a 1v1 scenario, so it's pointless
Yeah, his ability to turret dive is shit, especially compared to other split pushers. It is kind of frustrating, especially since even tanks can waveclear now with Titanic Hydra. I feel like the way to deal with this is rotating really well yourself, but it's harder, epecially pre-Dead Man's. Once you get Dead Man's, rotations are managable, but yeah it's another element of the game I'm having to learn for Nasus. It's a change in his gameplay, but change happens for everyone. The sands of time are ever shifting...
The only way I could imagine Riot fixing this is specifically giving Nasus some sort of mechanic to help him towerdive. It would probably involve a minor rework, and a couple other champions are already in line for that, so I don't see it in the near future.
we have overall faster games now, so that's a huge problem for him, if he gets behind it means he won't have time to farm up and come back
The snowballing right now is retarded. I agree that there's nothing we can do about other lanes snowballing, even less so now.
On the other hand, lanes are being won before Nasus's laner can start roam, which means that Nasus's laner doesn't have as much of that advantage over Nasus. Still, people get better at closing games at higher elo, so I would imagine that this is what's going to give you more trouble than me.
If Riot decided to tone down the snowball, it should favor us. If Riot decides that they like this snowbally meta, I would not be surprised if somewhere along the line Riot decides to give the slowest scaler in the game a buff to keep up in the meta. I think higher stacks on champion kills (something like 6-->15) would allow him to match the pace of them game. Besides some base-stat buffs, this is the only buff I would consider appropriate.
Things that I sort of agree on:
juggernauts' update made them really strong, which was huge indirect nerf for nasus
Juggernauts were a huge indirect nerf to Nasus, but not becase they were played. I don't if know if Darius was getting past bans n your games, but I played ranked almost exclusively during the Juggernaut Meta solely because it was the only way I could assure I wouldn't have to face Darius (not even normals draft was safe).
So I rarely had issues facing juggernauts. I was having more issues with other champions that were getting through bans, namely control mages, because the Juggernauts+Fiora+Gangplank were taking their place on the perma-ban list (although I prefered to ban Yi over Gangplank because Silver Yi's are a lot scarier than Silver Gangplanks and Yi posed a threat to me 1v1).
it's not true there is less jungle pressure. to be honest, it's completely opposite,
I misspoke there. Because of the extra trinket ward, I haven't had as many problems with getting ganked or dove. The problem I am having is, once I see the enemy jungler coming, I back off and recall, but before I can even TP back to tower, the enemy top laner and jungler have already taken at least 3/4 of it's health. Riot says they are going to give towers even more health in the future soon, so it's k.
every sated devourer jungler destroys him
The only current Sated Devourer junglers (Kayle is a problem of her own kind) that give me trouble are Xin Zhao and Bruiser Yi (and Shyv to a lesser degree). Xin Zhao can gank, and if he camps me and puts me behind, then I won't be able to 1v1 him because I need more gold than average to itemize against him. Meanwhile, Yi actually can duel Nasus if he goes Bruiser-Yi with Dead-Man's or something (Full-assassin Yi gets rekt).
I haven't really had that much of a problem with SD junglers because wither dumps them, I agree but they're much, much harder to 1v2 against than other junglers once they finally show up.
Things I disagree on:
his teamfight was never good, but it's completely atrocious after tank items nerfs and nerfed tenacity
I still think control mages' fall is a huge buff to his teamfighting.
DMP does not make you as tanky as Randuin's, but you are faster. Mobility over tankiness generally makes champions harder, but harder doesn't necessarily mean worse.
And tenacity nerfs are a double edged sword. Yes, tenacity was a huge help to him in teamfights, but on the other hand, less tenacity means wither is more effective. And plus, tenacity doesn't save you from knockups/knockbacks/permaslows anyway.
enemy riven hit lvl 6 1-2 minions before you - you are dead, even under turret. that was not the case pre 5.16
Nasus doesn't have Frozen Heart at level 5, so he isn't "10 armor behind" then. Nasus didn't become more vulnerable to a level 6 instagib on 5.16.
Besides, Riven is pretty much always going to hit level 6 before you. Just back when you get close to level 6 because 95% of the time she's one step ahead of you and you probably want some armor before you pick up those last couple creeps. (I found that opting for three cloth armors+potions [boots if you had the money but you won't if Riven is contesting properly] is actually a better buy than warden's mail, because the attack speed reduction won't help you much and it's more expensive.)
huge amount of nerfs of his core items (frozen heart gutted, armor items being weaker overall, worse triforce).
Armor item nerfs, eh?
would like to have a word with you...
I've done some math. I'm almost certain that you need to regen ~48.3% of your health for the Grievous Wounds on Mortal Reminder to be worth more than LDR's passive (ask me for the proof if you want). Nasus doesn't deal 8000 Q damage in a fight to lifesteal that much, so LDR is a better choice against him. As for LDR vs the old LW, your bonus armor needs to be ~4.09 times your base armor, or 1.69 times if they have the %arpen mastery. So basically, auto-attackers will do more, and AD-casters will do less.
But, yes, Nasus has dropped in tankiness overall. I used to buy Randuin's a lot because armor+health+AS reduction just gave him good stats, but now I buy usually buy Dead Man's Plate instead because the decrease in tankiness was worth the huge boost to his ability to flank in teamfights and rotate accross the map. Doesn't mean you can't buy RO if you want; I'm just reminding you of the price Nasus pays for mobility.
As for his core, it was hardly "gutted."
Frozen heart lost 10 armor, Spirit Visage gained 10 MR. They cancel out.
Trinity Force changes are negligible. AS/AD/crit don't really matter, and trading 10% CDR for 3% movespeed is ok because if you really want that 3% movespeed back, you can swap two CDR quints (5% CDR) for two MS quints (3%) MS and lose nothing.
Merc Tread's got nerfed, yeah. You will notice the difference in tenacity if you go 0/18/12, but if you go 12/0/18, it's works out to be only a 10% difference in tenacity (.65*.9-.8*.85=-.095), which isn't that much. And like I said earlier, tenacity won't save you from everything.
new masteries being even more in favour of damage dealers
Yeah, masteries help damage dealers, but Nasus is a damage dealer (just a very tanky one, like Shyvanna). The damage masteries he can get help him more than the old because it's percent damage, not flat/% AD/AP. Plus, the defensive masteries are pretty good on Nasus too.
If you go 0/18/12, you get
5% bonus resistance
8% extra healing (or with the next patch, some extra flat health if you prefer that over sustain)
Reduced Summoner Spell cooldown (rip Tping to towers though)
5% damage to low targets
5% CDR beyond the cap
Phage passive on steroids
If you go 12/0/18
2% extra Q damage
2.5% lifesteal
2.5% extra damage
5% bonus resistance
8% extra healing (or with the next patch, some extra flat health if you prefer that over sustain)
Reduced Summoner Spell cooldown (rip Tping to towers though)
15% tenacity + slow resistance
3% health leech
All in all, I think Nasus is going to be fine.