I would say that  is a necessity on  just for the fact that  followed by a Twisted Advance is so effective for ganking and almost guarantees a kill. It's also be a good way to save your ass in a sticky situation.

Attack speed helps you clear faster, get your passive going a lot quicker, and applies red buff on your target more often. 

Magic pen could also work if you plan to be ganking non-stop, but you will notice a difference in your clear speed if you decide to run these. Also take into account that the jungle mobs have no magic resist so they will be of no use.

You don't really have a choice here. The bonus armor is necessary for tanking the jungle creeps, as well as tanking any counter attacks your opponents might have.

Scaling magic resist blues are really nice to have. They start to even out from the flat magic resist at level 9. Makes you a little more bulky at end game team fights. 

You could also go flat magic resist if the enemy team has a lot of early game magic damage.

I like to run movement speed because it allows you to catch people and get away from angry enemies a lot more effectively.

I know a lot of people like to run flat AP quints, but  base damage on his abilities are insanely high  and most likely 15 AP won't make the difference in a gank.

Summoners resolve: Bonus gold on using ? Don't mind if I do.

Tough Skin/Bladed Armor: Allows you to tank the jungle camps that much more effectively, also the returned damage is helpful for finishing off the small camps.

Durability, Veteran Scars, and Juggernaut: Health is so effective on  just because of his passive. The more health you get, the more your passive will heal you for.

Tenacious: The less time you're CC'd the more time you can do damage, sit on people, peel for your allies and just be annoying. It could also save your life in a lot of cases.

Legendary Armor: This mastery scales very well into late game. Even though you are only going to end up with a bonus 2.5 armor and MR every 100 you get, it is still better then not having it.

Honor Guard: Very nice mastery that makes it worth going all the way down the defence tree.

Summoner's Insight: Lowered cool downs on your  for one point never hurts.

Wanderer: Makes you run faster albeit out of combat. Still very useful for catching people.

Improved Recall: Less time you spend in base the more time you can be useful. May not seem like much but it does add up over the course of a game.

Mastermind: Lowers the cool down on  and  are more gold and more effective ganks.

Runic Affinity: Having more time on buffs means you can clear faster and gank better. Very nice to have.

If you plan to gank at level 2 get a point in  at level 1 then a point into and you`ll be good to go.

: Do not underestimate this ability. It is probably one of the best passives in the entire game; and, as funny as it sounds,  is one of the few tank champions with an actual tank passive. 

It`s your sustain in the jungle as well as a big part in keeping you alive in fights. Make sure your always looking at the passive counter to check if it`s up or not, it could just save your ass. It`s kinda hard to get used to, auto attacking on a champion with so many spammable abilities  but as soon as you do, you will become that much more deadly. Having team-mates or enemies that are really spam happy with there abilities are ideal with .  

: A high damage, low cool down, slow and knock back ability. What more could you ask for? having a 250 base damage at rank 5 makes this ability very potent. Just remember that is is a skill shot and does have a cast time with it. landing this at max range could be the difference between a kill and a getaway. Also keep in mind that it  forces your opponent to face the away from where they were hit, meaning you can combine this with a  for a devastating combination. 

: One of my personal favourite abilities in the game. There is nothing more satisfying then using this, the enemy burning their flash trying to get away and still ending up right on top of them, making them feel like an idiot. After the root goes off, you should position yourself to get the most out of your Arcane Smash. But be careful when using this ability. If your opponent uses there flash to get underneath there tower, it could end in disaster. Remember that using this spell makes you un-targetable for the duration, meaning you can dodge skillshots, or big AoE abilities. You can't dodge targeted abilities though. If you Twisted advance mid-spell, you will still take the full damage and any other affects.

: This little guy has the highest base damage of any non-ultimate ability in the game. Having 460 base damage (combining the impact and explosion), however this ability should not be maxxed until last. The biggest thing to these saplings do is reveal fog or war. If the enemy tries to juke into a bush while trying to avoid a gank, you can say NOPE and throw this little guy in there setting up for an easy root.

It is always a good idea to stack these guys up on a small camps at the start of a game. Place 1 sapling at 1:07 on your respective camp, and another when it gets off cool down.  Hold on to your third one until the camp spawns and then drop it. The camp should drop very quickly without anyone's help.

: One of the few counters to a heavy AoE team. Having a 20% damage reduction for your entire team is very nice, and can be the deciding factor in a big team fight. Always remember that this is a more defensive move then offensive, so always place this on your friendly carries to reduce the damage they end up taking. The damage is nice as well, but it is always better to hold onto it for as long as possible in a team fight to mitigate as much damage as you can.