Hey Guys,

my name is Keenax and this is my first guide. First of all I want ask you to tell me the reason why you downvoted this guide. You also can tell me why you upvoted it. For the reason this is my first guide, please give me some tips how I can do it better next time :).
But now stop wasting time with telling you that mainstream stuff ;). I made this guide because Olaf ( I will call him Brolaf most of the time) is my main champ and i really like him. He is a very good jungler and early ganker. His damage output is very high.
This guide is not that tanky like some other guides of Olaf. I prefer Olaf with more damage output. If you'd like to play more tanky with Olaf, chose some other guides from Olaf, they might help you more than this ;)

Pros:

- Very good, in my opinion the best jungler of LoL
- Insane early damage output and good ganker
- Increased attackspeed with low hitpoints Berserker Rage, that means that you will surprise some summoners with your damage output and they will just be like "WTF??"
- True damage with your Reckless Swing
- Not squishy, hard to get down after some life items
- Nearly unstoppable if you pop up Ghost and Ragnarok
- The fact that he is BROLAF?!?!?

Cons:

- The fact that he deals more damage with low life, let people overrestimate Brolaf's skills and let them forget that also Brolaf can die!
- You have to learn the limit of Brolaf.
- Often gets focused when seen as a threat.
- You have to land a hit with Undertow, if not, the gank will probably be unsuccesfully.
- Damages himself with his Reckless Swing.

For my playstyle I chose:
Greater Mark of Attack Damage
Greater Seal of Armor
Greater Glyph of Attack Speed
Greater Quintessence of Attack Damage

You maybe ask why I chose Greater Mark of Attack Damage and Greater Quintessence of Attack Damage and not the Greater Mark of Desolation. There's one simple reason: You gain armor penetration from your ultimate Ragnarok. The attack damage is really nice to clear the jungle camps faster and you also will have more succesfully ganks with them, trust me.

I chose Greater Seal of Armor for more surviveability at the camps and also for ganks.

Greater Glyph of Attack Speed also to clean the camps faster and get that early damage output for your important ganks. Greater Glyph of Scaling Magic Resist are a good choice for Olaf too, if you think about building more tanky. Try out which runes fits better with your playstyle.

0/23/7 are the masterys we go with. Just to be that little bit tanky but still have in mind that you will have ALOT of damage output because of your runes and your true damage from your "Reckless Swing". You may ask why I go that 7 in utility? Just to get that mana regeneration. Yeah, Brolaf is an AD Champion, but he really needs his spells and it would be very sad if you lose a fight because you couldn't use your Reckless Swing just because you had no mana. You may think that you are the jungler and you will have blue buff most of the time, but you are only a good jungler if you support your team, and that's why you will give the blue buff's (except the first you start with) to your mid lane AP caster. For that reason that mana regeneration is very imprtant for Brolaf.

We start with Vampiric Scepter not to lose some important life you will need to gank early. The Greater Mark of Attack Damage will give you more than enough attack damage in early game. After Vampiric Scepter we go for Boots to have some more important movement speed. Now you build a Wriggle's Lantern to clean that jungle camps more faster. Now you have to chose if you go for Mercury's Treads or Ninja Tabi. You have to look whether the enemy team is more AD or AP heavy. After your Mercury's Treads or Ninja Tabi you buy a Phage and after that a Trinity Force. Trinity Force is a very good item for you as jungler, because you will be able to chase the enemys very good and it also has some nice passive effects. Warmog's Armor is the next item you will go for. Surviveability is one of the most important thing with Brolaf. After Warmog's Armor and some more Life, you get a Black Cleaver. This item will make you able to kill tanky enemys because of its passive. After Black Cleaver Bloodthirster follows. I know Brolaf's Tough It Out will gain him some nice lifesteal, but in my opinion it isn't enough, so we go for a Bloodthirster. And last but not least, you sell your Wriggle's Lantern and look for a tanky item. If they are AD Heavy you can buy a Randuin's Omen, if they are more AP heavy you can go for a Force of Nature. But also feel free to chose items from the "Situational Items" section. Now you will be very hard to get down, trust me. And your damage will be high enough to strike most of the enemys down. But dont overrestimate Brolaf! Think about how many enemys you can beat, but dont overdo it! If you think you will win a 1vs3, you might be wrong. Because of this you have to learn the limit of Brolaf ;).
However, if you need more surviveability and you feel like get killed too fast, think about building more tanky with some other items like Frozen Mallet, Frozen Heart or Banshee's Veil. Just look at the "Situatuional Items² sector and look for some other nice items. You won't build every game the same stuff, you have to be flexible to be succesful.

Here are some nice items you can chose too:

Atma's Impaler Good item with some armor and critical chance, also nice passive.

Force of Nature If the enemy team is AP heavy and you need more magic resistance, this item will be the right one.

Frozen Heart This is a good counter item for a team with many "autohit champs"

Frozen Mallet Take this instead of Trinity Force if you are thinking about to get more surviveability. The passive is almost the same and it gives you more health.

Randuin's Omen You can take this if the enemy team is AD heavy, this will be the last item in your build. If you think about building Randuin's Omen, don't forget to get Heart of Gold as fast as possible, to get as much gold as possible from its passive.

Banshee's Veil You also can take this if they are more AP heavy. The passive which dodges every 45 seconds a spell can be very useful.

Thornmail If the enemys are heavy AD with "autohit champs" Thornmail can be the right choice.

You also can take a Phantom Dancer instead of Black Cleaver if the enemys aren't that tanky.

Maw of Malmortius is a good choice, if they are heavy AP but you still need some damage output.

At Lvl one you skill your Undertow. Just spam the axes early in the camps, try to hit as most as possible enemys and immediately pick them up to reduct the cooldown. You will have way more damage output with this as if you would skill your Tough It Out first. With Lvl 2 it's time for your Tough It Out, pop it whenever it is ready not to lose important health, you will need it for your ganks. With level 3 you start to skill your Reckless Swing. Max it with Lvl 9. After maximized Reckless Swing you max Tough It Out and last you max your Undertow. Don't forget to Lvl up your Ragnarok whenever you can!

I chose Smite, as usual for a jungler, and Ghost. Why Ghost and not Flash? Lets think about it. If you really need to flee out of a fight or if you are chasing an enemy but he slows you, just pop up your Ragnarok and Ghost and you will be nearly unstoppable, trust me ;).

Blue -> Wolves -> Wraiths -> Red -> Small Golems -> Have a look if you have to gank or whether there is a good opportunity to gank. Notice! A gank is succesfully even if he just used Flash! But a kill is still better than that. If there's no opportunity to gank, clean the Wraiths or Wolves Camps again or teleport back to buy some stuff. You won't have problems at the jungle if you skill Undertow first. If you hit as much creeps as possible and if you pick up the axes immediately, you will have tons of damage and cleared the jungle so fast. This is very useful to surprise your enemys with early ganks ;)

!!!Notice!!!

I never tried this build in a ranked game, because I play rarely ranked games. If you like to play ranked games with this build, try it, and tell me the result :) . This build works great in normal games.

I hope you enjoyed my first guide :). Please leave a comment below if you voted for this guide, and tell me why you votet up or down. If i had any grammatical mistakes in this Guide, please don't take it that hard. English is not my mother tongue and I'm only 16 now.
Thank you for reading this guide and don't forget to leave a comment and a vote ( only positive votes! :D). Special thanks to all those guys, who commented already and gave me some tips to get a better build. You helped me so much, thank you.

Kind regards,
Keenax