Major update on June 8, 2011
Welcome one and all! I would like to first say a quick thank you to everyone that has read, rated, commented on the guide, subscribed to me on youtube, etc. Your support over the past year has made my guide the highest rated guide of all time on leaguecraft, and I truly appreciate the feedback and kind words.
I first published this guide more than a year ago in May 2010. At that time there was no such thing as ranked games, there was no established competitive scene, and people still looked to the "top 500 players" list that Riot put out to see who was the cream of the crop. I started playing LoL in open beta and had a few hundred games under my belt (with a hefty chunk of them being Nasus games) before I ever pondered authoring a guide.
Needless to say, a few things have changed since then. Metas have shifted multiple times, dozens of new champions have been released, and the community has developed drastically in terms of individual skill and in the competitive scene. That being said, I feel that Nasus is in a slightly different place in terms of power and viability than he was when I was a fresh level 30 summoner in the early days of LoL. Let's take a closer look at how Nasus fits into the current scene.
Who is Nasus?
The precise terminology gets a bit hazy in the case of a champion like Nasus, but essentially he can be classified as a "DPS tank", an "off-tank", a "bruiser", an "anti-carry", a "pusher", or all of the above. Nasus is a powerful late game champion that requires a good amount of farm and some good team coordination to be truly effective.
Why do I rarely see Nasus?
Depending on the elo you are playing in, you may or may not see much of Nasus. Nasus has the potential to be an incredibly strong champion. Unfortunately, he also has a few major weaknesses, which I illustrated in a rather lengthy General Discussion http://www.leagueoflegends.com/board...d.php?t=371291. In short, his skill set (specifically his ultimate) and the fact that he does not possess any form of CC reduction or gap closer that the current top "tanky DPS" in the game do, make him extremely susceptible to kiting. Because of this fact, his effectiveness is very dependent on both ally and enemy team composition. These limiting factors make Nasus a relatively situational champion choice. Under the right circumstances he can prove to be very strong, but if these circumstances are not met his success can be somewhat hit or miss. In comparison, there are other threatening tanks and beefy DPSers that are much less situational, meaning they are almost always very strong picks and are not so easily shut down or countered.
This is the real reason that Nasus, an otherwise potentially very strong champion, still isn't seen much in mid-high elo ranked games.
When to play Nasus
Nasus lacks any form of initiation, so he needs allies that can make up for this (Ashe, Warwick, etc). He also needs solid crowd control on his team to help counter his kiting weakness and keep the team fight in his vicinity (Amumu anyone?). In normal games where you can only see your own team composition you will need to decide whether Nasus will work well based off of that. In a ranked game you can also see the enemy team composition and choose accordingly. Nasus is great at shutting down DPS carries, melee heavy teams, and teams with lots of high HP champions (due to the % based nature of his ultimate). If you see the enemy team coming together with lots of tanks, melee, and physical DPS, with lacking CC, feel free to let the dog out of the cage and obliterate everyone.
When not to play Nasus
Nasus does not make a good main or sole tank. He is only truly a tank with his ultimate, he lacks initiations, and he has no means of protecting carries. If your team lacks another tank or off-tank he might not be a good choice. If your team has no initiation, he might not be a good choice. If your team lacks crowd control, he might not be a good choice. If the enemy team has loads of slows, knockups, and other kiting abilities, he might not be a good choice. Don't take this to mean if you see an enemy Ashe you can't play Nasus. But if the enemy team has "kite" written all over it, Nasus is not a smart route to go. That's a lot of situational criteria, huh? That's kind of the problem.
Why should I play Nasus?
Nasus literally has unlimited potential. If you can pick him under the right conditions, farm his Q well, and itemize smartly, you are playing possibly one of the the most terrifying champions in the league. Nasus is not a button-mashing face-rolling champ that can pub-stomp and carry evey solo queue game. He requires good awareness of team composition, awareness of the flow of the game, mana conservation, last-hitting, timing, and other skills that will make you a much better player. If you learn to do these things well it will truly pay off and not only will your Nasus will be a beast, you will be better at the game. For those of you that are just starting out with the game, don't be afraid to pick Nasus. Newer/low elo players do NOT know how to counter Nasus and you can absolutely wreck people!
GUIDE CONTINUED AT SOLOMID LINK.
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http://www.solomid.net/guides.php?g=151
http://www.youtube.com/watch?v=yaTo_R2TV4E
Authors Notes:
Frequent guide updates have made it increasingly difficult to keep both the leaguecraft and this version matching and up-to-date. I also greatly exceeded the character-per-post limit which was forcing me to truncate my guide to an increasing extent. For these reasons I have taken down the guide and just left the introduction link to the full version. The guide in it's entirety can be found here: http://www.solomid.net/guides.php?g=151
I apologize for any inconvenience this may cause but felt it was necessary to maintain the guide at it's highest quality and in the form intended.
Thank you for the all the continued comments and feedback! I am continuing to update the guide with bits of useful information recommended by readers.