Hi, and welcome to my Olaf guide.
As an norwegian, i am obliged to at least buy Olaf the berzerker, and in my chase, use him.
I play Olaf as the tank you realy can't ignore, and burning all cooldowns on him to kill him is in most chases a must, leaving the enemy team with few cooldowns to face the rest of my team with.

In this guide i will share with you my this far sucessfull Olaf tank build.

I run with rather offensive glyphs, this is to give me more damage, making me more scary in the field.
Greater Mark of Desolation Extra Armor penetration, together with your ulti, you can deal huge amounds of damage to enemy tanks as well as low armor melee champions.
Greater Seal of Evasion Gives some neat dodge that might save your life on the field, together with Evasion it will give you a whooping 6,75% dodge and some sweet movement speed on proc.
Greater Glyph of Scaling Cooldown Reduction I use these simply because thats what i got. Pretty neat, but Greater Glyph of Attack Speed is probably better.
Greater Quintessence of Desolation Again, more armor penetration to bring down heave armored foes.

The masteries is very common tank spec. All the sweet stuff from the Defensive tree, and attack speed from the offensive tree. Changing the attack speed in the offensive tree to cooldown reduction is also good.

[Berzerker Rage]]
For each 1% of health missing, Olaf's attack speed is increased by 1%.

This passive is what makes Olaf so scary, peoble tend to burn their cooldowns early when fighting one another, maximising this abiliys potential.

Undertow Olaf throws an axe to a target location, dealing 50 / 90 / 130 / 170 / 210 (+0.5 per attack damage) physical damage to units it passes through and slowing them by 24 / 28 / 32 / 36 / 40% for 2.5 seconds.

If Olaf picks up the axe, the ability's cooldown is reduced by 6 seconds.

Cooldown 10 seconds | Cost 55 / 60 / 65 / 70 / 75 mana | Range 1000

I max this ability first because i use it as an harassment spell. And when chasing people this spell is almost spammable as the cooldown is reduced by 6 seconds if you pick up the axe again.
This spell is the key in my build to early kills!

Tough It Out For 6 seconds, Olaf's attack damage is increased by 7 / 14 / 21 / 28 / 35 base damage plus 1% of his max health. While active, Olaf gains 9 / 12 / 15 / 18 / 21% lifesteal and spell vamp.

Cost 40 / 45 / 50 / 55 / 60 mana | Range 700

This spell is your key to survival. The later you use it, the more damage you will deal due to Olaf's passive. In 1v1, using this at about 20% HP will give you about the lifesteal you need to stay at those 20%, and thus having 80% more attack speed.

Reckless Swing Olaf deals 100 / 160 / 220 / 280 / 340 true damage to his target and inflicts 40 / 64 / 88 / 112 / 136 true damage to himself.

Cost 50 mana | Range 325

This spell is so great, as you deal true damage with it. Rammus got freaking ton***** with armnor? Does not matter, this spell ignores that pesky armor. The damage you deal to yourself is not a big matter, have never ever killed myself with it this far.

Ragnarok Active: For 5 / 6.5 / 8 seconds, Olaf is immune to disables and reduces incoming damage by 20 / 30 / 40.

Passive: Olaf has 10 / 20 / 30 increased armor penetration.

Cost 100 / 75 / 50 mana | Range 400

Olaf's ultimate Ragnarok matches perfectly with his passive. Making him immune to diables when active and reducing incoming damage makes you deal tremendous damage when on low HP.

I run with the good old Ghost and Exhaust when playing Olaf.
Ghost Great for chasing, and together with your ultimate, it makes it easy to escape ganks even in 5 on 1.
Exhaust I use this to pick up early game kills and to get overkills in 1v1. Also good to use as a signal to team to which target to nuke first in teamfights.

Time to take a look at our arsenal of armors and weapons:
I always start with Dorians Shield. It gives all the needed stats for a tank, and thus giving you high early game survivability.
The boots is always the most tricky part in the item selection on any champion. I usualy run with Berserker Greaves as Olaf benefits good from attack speed adn it gives you more damage. You know all about boots, so take the ones you think you will benefit the most on in that particular game.

After boots i build my Phage HP, damage and slow proc gives you exactly what you want early game.
Warmog's Armor is essential for Olaf. You want more HP per percent of you HP pool to benefit as much as possible from your passive.
Now, finish your Frozen Mallet and start building your Force of Nature. Of course, DON'T build Force of Nature if the enemy team is low on AP users, Replace either with another Warmog's Armor if you are doing well or Randuin's Omen if those melee champs are dealing alot of damage on you.
Now, let's build that Atma's Impaler to make you even more scary, if you have two Warmog's Armor your damage will skyrocket.
If you make it to late, late game buy that Guardian Angel just to be an arse.

There is one keyword when playing Olaf. Patience! The later you use your cooldowns, the more damage you will deal. This is what makes Olaf a rather hard and gutsy champion to play as.
I will not stop saying it: Delay your cooldowns, use them as late as possible.

Okay, farming minion waves:
Believe it or not, Olaf is great at farming minion waves. Undertow through wave, run straight through, pick up axe, throw it back again. Ching! Loads of gold for you.

Harrass:
Use your Undertow spell to harrass enemies, if possible, try to pick up axe again. Continue with this untill you want to go in for the kill.

Chasing and killing:
Positioning is a keyword here. You want to be able to pick up your axe after you throw it, so plan your assault carefully. When engaging, Undertow your target and leg it. Your enemy will have Three choises:
1: Fight you head on and most sertanly loose (You don't chase after people if your life is at too big a risk) as Olaf is realy strong when faced head on.
2: He can run straight back to tower, and with your possitioning you will pick up axe over and over again giving you infinite slow and loads of bonus damage.
3: He can run a detour around you axe, forcing you to not pick up axe, but he will have to run longer.

In most chases this is a kill for you, and when even the tank on your team gets kills, the game just have to end well.

Olaf is also very strong two on one. Use Undertow, Reckless Swing and auto attack to bring down first opponent. You will now most sertanly be on low HP, and your last enemy will be very confident about killing you. Ragnarok and Tough It Out are off cooldwon, and you just burst your second enemy down with almost double the damage than before. This will in most chases not be predicted by your opponent, scoring you a double kill.

Now i have given you some scenarioes, and you may be thinking: "Okay, let's do this". Note, you need to read your opponents to sucessfully roll faces with Olaf. Noobs will just burn all their cooldown early, bringing you down to 30% ish and making it easy for you to burst them down. Skilled players on the other hand will save all their cooldwons to when you are low on HP, and THEN nuke you. This is when it's vital to use Ragnarok at the right time, which is right before they nuke you to heaven.

Sorry about wall of text there, but there is so much to say about Olaf's gameplay.
However, i have marked the most important parts with red letters to make it easy to find the most essential points.

Thank you for reading my Olaf guide, and i hope you learned something from it.
Just remeber to be ice cold when playing, and to read you enemies. This will make you a sucessfull Olaf.

Cheers and GL HF!