Hello, this is my FIRST guide. So i want really hear comments how can i do this guide better.
This guides idea is Tank/Farm and it happens with Undertow and Tiamat. How? Well i use splash damage in little before late game i kill mass of minions because of splash damage.
I apologize this guides outfit.

I picked Ghost and Smite. Ghost is because Olaf doesn't have any itself escape mechanism. And with Smite i can steal enemy junglers Red/Blue/Baron buffs.

I like start with Doran Shield because i get good cover until i get my next item, Mercury's Treads. Why Mercury's Treads? Because i get Magic Resist and Tenacy what is almost always needed for hard CC's. And i usually buy Chalice Of Harmony directly when i got enough gold.
Rest of them you see top of this guide. And all those health items, runes and masteries is for AD and i get it from Atma's Impaler i don't need more AD than that.
When i got enought money i make space sell Tiamat and buy one of these: Infinity Edge, The Bloodthirster or something else.

1/21/8.... it's interesting, isn't it? Well i wanted get the bonus gold from Smite that's why there is 1 in offense.

I took APen marks, Health seals, Magic Resist glyphs and Flat Health quints. All those Healths are for Atma's Impaler and APen is for AD and Magic Resist for more MD cover.

I take one point of each then i max Undertow because i can slow enemies for my team especially team fights. Then i take Vicious Strikes because i can destroy turrets with it's AD boost and Reckless Swing is usually my low health champ killer but only in the late game when it's max.