21 9 0 is entirely viable for many play styles. 24 2 4 gives you extra damage/cdr/ms for clearing and ganking, while retaining the 2 points in D for jungle survive. If you run in balls deep with this build you're going to die anyway. It is best played sort of similar to Talon. 25 2 3 might be better, depending on your play style. The point in enhanced recall is more personal preference; it allows you to get away from situations such as split pushing (which hydra kong is extremely good at) and assassinations in the enemy jungle. It could be put into Dangerous Game (25 2 3); the reason I don't do this is because that mastery is only useful when it comes to team fights in the mid-late game and you have to actually be getting most of the kills for it to be useful even then. In saying this, damage Kong often does get many kills in team fights, as he is not the primary initiator and thus gets off a ton of damage.

Armor seals and scaling MR glyphs are standard. You can take flat MR glyphs instead if you are a player who like to early engage a lot to begin snowball.

Wukong gets 30% armor shred from his Q, so arm pen runes not really required. He gets a lot of AS from his E (first ability to max), which you lead with at each jungle camp, so AS runes not required either. He doesn't really need MS quints, as he has great gap close with w and e and escape with w. He gets MS from his ult at 6 also. He scales EXTREMELY well off AD, so going flat AD quints as well as marks is the way to go.

A good way to figure out what your starting item will be is to look at whether or not you will be building a jungle item. If you are, machete is usually a good idea. If you are a champ with a lot of AS, or one who wishes to early CJ, DB can be a better pick... Even if you wish to build a jungle item afterward. Machete is often a good pick on junglers who cast a lot, due to the increased damage. I prefer Machete to DB on Kong, as I like to rush into my jungle item for a bit of much needed sustain and extra gold.

Taking ward trinket is great, as it lets you secure your own jungle or even better... CJ. I like to put it in the bush by the enemy wraith camp, or alternatively buy wards to keep vision there and place it elsewhere. Wards in the enemy jungle let you CJ and even better... Counter gank. They also stop your team from getting ganked. Always worth it the gold, always do it if you can safely place the wards. It will pay off.

First to rush is stone > t1 boots > VS. This will give you your much needed sustain and ms, the 2 things that every jungler must have.

After this, you have a few options. Lizard for gank burst and gold increase, Mercs for movement around the map, tiamat for faster clear and gank burst.

Go Merc if: Gank opportunities across the map, requires moving faster between lanes to capitalise.

Go Tiamat if: You want to destroy your jungle camps. This gives you more time to do other things.

Go Lizard if: You want some extra single target damage for gank power, while also wanting a bit more gold. E.g. Gank mid, take 1-2 camps, revisit mid, 1-2 camps, mid etc.

Last whisper is a must have damage item, however you must get it at the right time. The time to do this is usually after you have completed 2 other damage items, sometimes just 1. Because of this, you usually want to take it after Lizard, Mercs and Hydra for a big damage increase.

You NEED GA as you are pretty glass cannon. Buy it 5th... Occasionally even 4th in certain situations.

Lastly, take Tri Force. This lets you assassinate carries with ease. The reason why you leave it til last is that on Wukong, Tri Force is good but not cost efficient. It has many stats that don't benefit him, so other items such as Hydra are just better earlier in the game. Hydra gives you item proc burst as well as MUCH more.

This build is very effective. The build order is situational but there are not many other items that can be switched in. I will explain some of the alternatives and why I don't usually build them...

Cleaver: Very popular on Kong but not good on full damage Kong. This item is a MUST if you are the main initiator, as it shreds enemies armor for your carries to follow up on, but does not provide as much damage if you are part of the follow up engage.

Warmog: Viable in certain situations, however seeing as you are kinda glass cannon, pure damage and a GA is just better.

BT: Great damage and sustain, however Hydra is better. Hydra, while 25 AD less, provides you with insane clear. Clearing with a BT is slow. Because of the proc on Hydra, it actually gives similar damage anyway.

Mallet: Like mogs, gives you some nice health which you don't really need, considering the damage loss. The slow is nice but by the time you get this item, it won't help that much at all.

You must take smite.

I highly advise taking flash. Doesn't really need to be explained. W into flash after your damage combo will save your life over and over again in team fights.

Ghost can be taken instead of flash if you want to get some extra speed for ulting through teams, however I would not recommend this, as you already have gap close (w) and MS (ult). Only really viable you you are going tanky initiator kong and even then I would still advise flash > ghost.

The farming vs ganking decision can be a difficult one with Wu. He doesn't reach his full potential until he get his rank 2 ult at level 11 and gets a decent spike at 6 also, so farming your jungle (or the enemy's) can be a good plan in many situations. In saying this, he can successfully gank any lane due to his stealth engage and gap close, so if you see a chance to gank/camp and begin a snowball you should definitely take it. He is a jungler who can very successfully camp the mid lane and then snowball the game. Farm vs gank decisions are ultimately up to you and your play style, as Wukong benefits from either.

Wukong has been seen a few times in pro play now. He has been used in two ways only... As AD Carry mid lane and tanky initiator from the jungle. The main reason he is not viable top at that level is that he can get pushed to turret and dived early. The reason he has not been played as a carry from the jungle is that typically, junglers at that level sacrifice farm to make a large number of plays for their team. He is occasionally played as early damage from the jungle, transitioning into tanky initiator later in the game. You can do this by building items such as Lizard instead of Golem.